Engine/Trans Advice

[nac593]

Hi, I'm new here but i've been watching the forum for a while. I have a 69 shortbed that needs a new engine. I am pretty sure i'm getting a new gm crate engine. Just the basic 350 longblock. So here's where I could use some advice. I would like to get this 700 transmission I've been reading about with the overdrive. I'll be using the truck as a daily driver. But my dad says I can have his trans from his chevy dually. TH400 I think? Sounds a lot cheaper to use my dads, but it's been sitting for probably 7 years. Is the torque converter and the other parts still usable? Would it be less headache to just buy the new trans and get it over with? My dad said all I could do is put it in and see if it works. I want a reliable truck. By the way, I'll be switching from the 3 speed manual to automatic. Also I read you have to shorten the driveshaft with the 700. Also with the 400 , or no? Any advice would be appreciated. Thanks!

[ksjh1316]

The 400's are hard to kill just rob some hp. If the tranny ran fine just change the seals on it as well as the fluid and you should be fine. Yes you have to change the front section of your drive shaft to have it match up but you can usually purchase one off the board for pretty cheap to get your driveshaft to the right length. Are you going to just run a floor shift with this combo or change out the column?

[SactoJim]

Many years ago I switched from a "3 on the tree" to a TH350. Things you need will be:

Auto crossmember
Drive shaft mods
Auto linkage
Trans cooler
kick down cable and carb brackets (400 similar but electric)
Automatic steering column (if not doing a floor mount type shifter)

Those are major ones that I can thing of at the moment.

TH400 is a good tranny and REALLY good if it's free, but after sitting that long you should at least put new seals in it. You certainly don't need it behind a mild small block and it does take more hp to operate than a 350 or 700.

I'd lean torwards the 700 because it would simply make your truck more fun to drive. The 700's lower first gear will get you off the line quicker and you will get the added benefit of an overdrive.