Cab too far gone...?

[76Silverado]

I bought a 1976 2wd 1/2 ton Silverado in December, 03 which I am trying to restore. The previous owner installed a new 350 crate motor, a rebuilt 700R4, new rear end, drive shaft, and new brakes. Mechanically the truck is in great shape and I have been driving it to work 25 miles each way daily. The cruise, A/C, everything works, believe it or not.

The body is a different story. I have rust in the usual places and will probably have to replace quite a few body parts. It seems like most of the truck is covered in surface rust with a few holes here and there. What has me the most concerned is the cab. I have discovered that it is leaking water through the firewall which has caused the passenger side floor to rust out. I think the water is coming in through the cowl area as the seam sealer is all cracked and deteriorated. I covered the seam with black automotive silicone which I think has stopped the leaking for now. However. it looks like there is space between the cowl and the firewall that I cannot see and could be full of rust. I was wondering if anyone else has experienced a problem with water leaking in through the fire wall and how they fixed the problem. I'm afraid I might spend alot of time and money fixing up the cab and interior, only to have problems later on with water getting in. Aside from the floor, each cab corner has a small rust hole (about 3/4" in diameter). The rocker panels, cab supports, etc. appear to be okay. Would you recommend welding in a new cab corner for such a small hole, or could I just cut all of the rust out and repair the area with fiber glass? I know I am going to be welding in a new passenger side floor. That is, unless I end up ditching the cab and finding a replacement.

Thanks for your help. I found this forum through Chuck's Chevy Truck Page which I have found to be very helpful. I live in Houston, Texas so I don't do any snow plowing. If there is even a trace of snow here its a major event with school closings, etc. However, I am a Chevy truck man. So far I have owned an 81, 85, 88, and now a 76. I also used to own a 77 El Camino, but don't if that counts as a truck. :)

Thanks,
Scott

[Pelican]

Welcome to Snowplow-Contractors!!!:drinkup

You might have better results down there with fiberglass, but up here due to the harsh environment, fiberglass is just a band-aid and rarely lasts more than a year.

I don't think you'd have much trouble finding a rust free cab down your way. I've done it both ways, restored a rotted truck with patch panels and restored another with a rust free cab, the results were much better with the new cab. It's not as hard as you might think.

[79chevybigred]

When your sure of where that leak is man let me know. I've been chasing one for quite a while on the pass side. Tried the cowling with silicone but still a small leak runs down the kick panel on the pass side. Checked the the tubing between the door and pilar where the wires run, thats good. and the windshield seal is good. so hey if u got any other ideas to check let me know. maybe mines in the cowl 2 just havent got it yet. But down in texas fiberglass would go good. like pelican said about the fiber glass that wouldnt even last me 2-3months in the cold here in alaska. Plus youd be surprised what kind of cabs u can find also.

[76Silverado]

Thanks for the replies. My leak is definetly in the cowl area. I tested it this weekend with a water hose and it doesn't seem to be leaking any more. Mine was leaking where the floor meats the firewall behind the glove box area. However, I wouldn't be surprised if your leak near the kick panel is coming from the cowl area also. You may want try some of that brushable seam sealer available from Eastwood.

I have my eye out for a whole truck body that is cleaner than mine. If I can find one, that might save me alot of work as my bed sides are fairly rough also. The only problem with changing the cab is that I'm not that confident in my ability to get all of the wiring back together correctly. Currently, everything on the truck works, including the cruise control and A/C. Once I take everything a part, I'm not sure I can get all of that stuff working again. I'll probably keep working on patching the truck up, but also keep my eyes open for a clean body replacement. I found a 78 Silverado with a very clean body (no rust) except for the hood, but the guy is asking $2,500.00 for the truck. That seems pretty high to me considering the motor is seized and he doesn't have the title. I'm sure he would sell it for a little less, but I was only going to offer him around $500.00 to 700.00. Even the front fender are rust free, which is pretty unusual from what I've seen. But, I guess I'll keep looking.

[Pelican]

As you disassemble, tag all the wires with masking tape at both sides of the plug, or at the accessory the wire services. When I did my swap, I swapped my existing harness to the new cab to be sure everything would be the same. Just be methodic and patient, it's not all that bad.

[76Silverado]

What did you guys that swapped cabs do about the Vin numbers? Suppose I use an 80's something cab. Can I just swap the vin plates on the door jam and throw away the vin plate on the dash of the 80's model cab since the 76 model doesn't have a vin on the dash? There are some advantages in Texas to having a truck that is more than 24 years old as you don't have to worry about smog testing or having catyletic converters, etc.

If you use an 80's something cab is it easier to also use an 80's something front clip since the hood hinges are different? Also, if I use an 80's something cab, do I have to use an 80's dash? The reason I'm asking is I can probably find a clean 80's cab and front clip alot easier than one from the 70's.

[Pelican]

I swapped the VIN in my cab, I avoided a lot of paperwork by doing it this way.

Can't help you with the other questions, my swap was with a Ford.

[rwiesesr]

Originally posted by 76Silverado
I bought a 1976 2wd 1/2 ton Silverado in December, 03 which I am trying to restore. The previous owner installed a new 350 crate motor, a rebuilt 700R4, new rear end, drive shaft, and new brakes. Mechanically the truck is in great shape and I have been driving it to work 25 miles each way daily. The cruise, A/C, everything works, believe it or not.

The body is a different story. I have rust in the usual places and will probably have to replace quite a few body parts. It seems like most of the truck is covered in surface rust with a few holes here and there. What has me the most concerned is the cab. I have discovered that it is leaking water through the firewall which has caused the passenger side floor to rust out. I think the water is coming in through the cowl area as the seam sealer is all cracked and deteriorated. I covered the seam with black automotive silicone which I think has stopped the leaking for now. However. it looks like there is space between the cowl and the firewall that I cannot see and could be full of rust. I was wondering if anyone else has experienced a problem with water leaking in through the fire wall and how they fixed the problem. I'm afraid I might spend alot of time and money fixing up the cab and interior, only to have problems later on with water getting in. Aside from the floor, each cab corner has a small rust hole (about 3/4" in diameter). The rocker panels, cab supports, etc. appear to be okay. Would you recommend welding in a new cab corner for such a small hole, or could I just cut all of the rust out and repair the area with fiber glass? I know I am going to be welding in a new passenger side floor. That is, unless I end up ditching the cab and finding a replacement.

Thanks for your help. I found this forum through Chuck's Chevy Truck Page which I have found to be very helpful. I live in Houston, Texas so I don't do any snow plowing. If there is even a trace of snow here its a major event with school closings, etc. However, I am a Chevy truck man. So far I have owned an 81, 85, 88, and now a 76. I also used to own a 77 El Camino, but don't if that counts as a truck. :)

Thanks,
Scott

[rwiesesr]

Scott: I live near Conroe and have a '75 Scottsdale I broght with me when I transferred down here from Nebraska almost 20 years ago. I too have a really bad cab floor but I plan to repair it if at all possible. I do not have holes in the firewall but there are some holes in the cab floor.

I am just beginning to move into restoration. "Ole Blue" has tons of miles (the odometer was not working for almost two years) so I am estimating I have around 200,000+ miles. But the 350 cid engine purrs like a kitten.

I also am beginning to look for parts. Mother (my wife) lost a battle with a dumpster so I need another bed. Ole Blue is a long bed edition.

Glad to hear there are some of us down here along the gulf coast.

The Ole Timer

[76Silverado]

It's nice to see another Houston member Ole Timer. I'm not too far away from you. I just moved from Spring, TX to Cypress, TX. However, my buddy who has a mig welder and is going to be helping me with this project just bought a house in Conroe. So, I'll probably be working on the truck right around the corner from you. What's really weird is the guy I bought my truck from called it "Old Blue." My truck probably has about 200,000 miles on it. The odometer reads 75,000 and the maintenance records go up to 1988 when it had about 80,000 miles. The previous owner, who also lives near Conroe, told me he drove it for a few months with the odometer not working. He got the truck from his father who bought it new.

[PROMOWER]

When I did this, I used an 85 cab on a 76 chassis/body. Have to change the wipers aroun a little as the newer cabs have that filler piece by the windshield, and the old cab had the hood going all the way to the windshield. Wiper switch is on steering column in newer truck. Steering column wiring is different, as highbeams are in steering column, not on floor. Have to weld up area where hood hinges are in newer cab, or water will get in and rust cab. if using old style hood, must use old style fenders because hood hinges bolt ot inside of fenders. Headlight wiring is different. new trucks had 4 light system, old had 2. Must modify to work or use old harness. If 2wd cab going on 4wd chassis, floor hump is deeper on 4wd, so must modify floor. Insides of doors are differen. Use doorpannels that go with doors. Old dash will cover VIN in newer truck, then just rivet old VIN tAG IN DOOR JAM WHERE IT BELONGS, BUT OLD VIN WILL STILL BE IN CAB SO YOU'RE NOT ALTERING IT. JUST KEEP RECEIPT FOR CAB WITH vin # IN SAFE PLACE in case of problems. Cab mount bushings are different. Must use mounts to go with cab you are using. Instrement cluster must be from same era as wiring you are using. Small differences in core support, but eithe will work with some small modifications. Radio antena in windshield in some years, usually after 1981. Just what I remember from mine. JOHN

[al b]

You may find your water leak at the windshield. Water comes down the glass and goes around the glass(underneath the rubber) and then into the vehicle. Right side only....I don't know why it only happens on the right. To check this out, take your dash pad off of the dash and look in the corner. Nine times out of ten there is a problem with the water getting in. I have replaced two cabs on different trucks that I have owned, and that was always a weak spot. The fix?... You could urethane the windshield in, but that makes it very difficult to change later. You could clean the rubber out very well (where the glass sits), use some silicone emulusion, and then when installing the windshield, wiggle it to death to seat the rubber and the windshield together. Hope this helps.

[1978K5]

Swapping out for a new cab is easy. I did this with a '71 I had and it took one weekend to do it. Fixing one that isnt too bad isnt a bad way to go, as long as you take into account how much time you will spend on it, AND how much your time is worth. As far as the VIN's are concerned, Im not too sure if the Fed regards the cab as the main part of the truck or the frame. I know on a car, the body is the main part and swapping the tags is a federal crime. I encountered that when I went to rebody my '70 Camaro with a '71 shell, imagine the disappointment. Anyhow, I picked up a rust-free cab for my '71 for $850 and it included both doors and all glass, so I know the prices arent too steep. Im presently considering whether or not to rebody my Blazer, the body swap I know would be easier and overall less time consuming. Good luck with your project, sounds like a nice truck.