I just bought a 1985 trans am, and Im wanting to put in the 350 engine, and Turbo 350 in, and im trying to figure out what kind of driveshaft i need for it to work

 

I am almost positive you will have to have a custom shaft built. Since the TH350 is shorter than the 700R4 or the T56, you won't be able to use the stock shaft. You may be able to get some measurements and find the right length in the junkyard but good luck with that. Spend a little bit to be safe and have a good balanced shaft.

 

you can use parts off an'82 third that came with a
th200c(driveshaft,torque arm,crossmember,etc.)
to install a th350 into a third that originally came with
a 700r4-will need the torque arm adaptor kit though.

 

Well there you go. I just learned something new today

 

or you could get a 9 inch tail shaft th350 from a half ton p/u their the same length as a 700r4 and their geared similar as a car you probably just need adapter u joints.

 

Thanks for the help guys, the long tailshaft 350 fit just right.