What differential ratio for daily ride?

[ramptester]

I have a 1993 Chevy SWB Reg cab with the stock TBI 350 motor and auto with OD. It is a great truck, but the rear axle seals have begun to leak and have ruined the brakes. My question is: When I do the repair, should I go ahead and put a 3.42 in the rear from the original 3.08 if I want a bit more performance and better pulling? What would my engine rpm be at 75 mph with this setup and tires that are about 1/2" taller than stock? Also, for a daily driver, do you recommend posi or would you stick with the reg differential?

[Alan]

The 3.42 was, and may still be, the standard ratio in the 1500. I had one with a 305 and 3.73 with OD and it worked pretty good. The small small block needed the extra gear. That truck got 11.4 MPG towing a 24' Grady-White from NJ to VT.

I tried a 350/3.73/OD combination and mileage was in the 12 range running empty in the Interstate (only one tankful).

Depending on how hilly your area is and whether you tow heavy or regularly, I think the 3.42 would be a good choice. If you're often running a load in hilly conditions I'd go to a 3.73

[ramptester]

Thanks for the info. I will compare the differences between the 3.73 and 3.42 for my choice.

[ratlover]

373's are a nice ratio for a truck with stock tires or close to em especiall with an OD.

remember that you will have to change the front gears too if its a 4x4 so that will add to the cost.

a posi is a nice addition but I would stay away from a factory "gov lock" in a 10 bolt rear end. in the bigger rears they are ok but I feel they are too weak in the smaller axels JMO

[Lawngodfather]

Originally posted by ratlover
remember that you will have to change the front gears too if its a 4x4 so that will add to the cost. I was thinking that also.

Plus the fronts will cost a lot more to change too.