89 350 flex plate/flywheel question

[4chevyman]

I've got an 89 350 out of a truck.  I know this engine uses the old school harmonic balancer with an externally balanced flexplate.  My question is will this flexplate work with a turbo 350 torque converter?  The 89 trucks came with a 400 or 700r4 and I don't know if the converter bolt holes are the same.  Along the same lines, will the flywheel for this engine work with an old school 4 speed and what clutch should I use.  Thanks for the help. 

[Russ130]

The flexplate you have for an automatic will not work with a manual tranny which uses a much heavier flywheel. The flywheel won't have big holes in it since the clutch actually presses against it to transfer energy from the motor to the tranny. It should bolt right up to any GM auto tranny. On another note the 350 is internally balanced not externally like the 400.

[4chevyman]

My 89 350 is a one piece rear main.  These engines are kinda a mix between internally and externally balance.  The harmonic balancer is the same as the 2 piece rear main, but the flex plate has weights welded to it like a 400 small block.  My question is does the turbo 400 converter have the same pattern as the turbo 350.  they didn't offer the turbo 350 in 89 and the flex plate off a 2 pc rear main won't work on a 1 pc.  My other question was if I want to go with a 4 manual speed trans out of an older truck, would the flywheel for the 1 pc seal engine work w/ the old clutch and trans, or would I have to use a clutch that goes with the 89 truck or would this even work?

[Russ130]

As I said the 350 and 400 have the same bolt pattern as well as the 700r4. As far as the inchange between manual trannies I have no idea. I would think the clutch would have to come from the tranny due to the splines on the input shaft matching up correctly. I wouldn't be surprised to find out they do indeed fit both old and new flywheels.

[Captkaos]

you can use the flexplate with a TH350 if it lines up.
For a 4 speed you need a flywheel, but if it is a 89, it should have the same as a normal manual trans.