Tranny swap.
 

I'm looking at a deal for a 700r4. I've been threatening to swap my th350 for one since I got the truck. My thinking is that it will increase my MPG, and will increase longevity of engine because of fewer RPM @ highway speeds. Am I correct in the assumption that it will improve MPG (mostly in-town driving)?
Also, what is it gonna take on a scale of 1 to 10 to do the swap? 1 being a direct bolt up; 10 being a torch, an act of congress, and the will of the almighty himself.

Look in the FAQ, I wrote one up that covers everything I could think of at the time. ;)

Don't even try to justify it on a cost basis; you're looking at a lot of miles before the MPG improvements show up as a fatter wallet after taking the hit that a 700R4 is. Do it for the lower cruise RPMs and shorter first.

You will gain in MPG; the 700R4 is what pushed my truck from a 10mpg wonder (TH400) to a 14mpg wonder. I have clocked it as high as 17 if I drive reeeeeeally carefully.

Scale of 1-10, I'd say a 4...it's really not too far beyond a bolt-up, but there are a few technical bits (namely, TV cable and TCC wiring).

Just FYI...your new cruise RPMs at a given speed will be, at most, 74% of what they are now, and that's if you either didn't put a locking converter in the 700 or if your TH350 has a locking converter. That's one of the other reasons I like it, is the 4th gear lockup.

I plan on doing the 700r4 thing to my 72......its 30 miles to anywhere i want to go so i figure its gotta help my mileage! from what i hear i will have to get a few inches taken off the drive shaft, the other things are simple wiring and linkage installs. i got some of my parts and information from the folks at 700r4.com. i hope it all works out!

Thanks, Guys. Goos stuff

Bottom line, if you install it CORRECTLY, you'll love it!