Transmission delimma

[scotts72]

I have a question and I'm sure I will get a lot of suggestions, I'm just looking for the best solution so I only spend the money once. I have a 68 with a SB350mild cam and TH350 trans, the Rear end is a 3:73 Posi, my dilemma is I live in Texas and the speed limits are mostly 70 so that means 75-85 here. I am wanting to change out the Trans to make the truck more efficient and enjoyable to drive instead of hitting 3500 to 4500 grand to just keep up on the highway and avoid being run over. Just wanted to see maybe which trans is the best replacement and has been reliable.

[yuccales]

Cheapest way I would think is a set of 3.08's in that rear end.

[novice]

Any transmission is probably going to involve change driveshaft, linkages, transmission mount location, etc.. So like yuccales suggest gears will probably be the most economical route.

However, that being said, 700r4 will give you overdrive. T56 would be my choice or a good 5-speed. I like shifting gears though.

[Bigdav160]

Since you already have an automatic the 200-4R is the easiest swap followed by the 700R4.

[Dead Parrot]

Daily driver only or used for a work/tow truck?

If it is primarily used as a commute/fun truck, change the rear end. Probably cheaper then a transmission swap. Just check posi compatibility. Not all rear ends/gear ratio combos will take all posi options.

If it needs to haul heavy loads or tow a lot, keep the current rear end and add the 700r4.

Use one of the on line RPM checkers to play with different options.

[Trucknut57]

I had the same problem in my 57'. Running at highway sppeds the engine was howling, so I switched the rear axle out for a 72 Camaro rear axle and that had 2.73 gears. I'm still running a th350 and now the engine humms along @ 2200 rpm while doing 75 MPH.