350 Flexplate Big Problems

I just got my first 350 with one piece rear main seal.
Now I find out it needs externally balanced flexplate.
All the parts stores say the flexplate is for 700r4 ,but I need to use a turbo 350.
Problem is the last turbo 350 was made in 1981 back in 2 piece seal days.
My engine is 1990.
Will a flexplate that fits 700r4 fit my turbo 350 torque converter???????
I know this is the best place to get answers.
Anyone got any part numbers etc?
Help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Done a little studying lately on the t350. From what I read, it seems from 86 on when the rear main seals on series 1 motors went to one piece. The flexplates for these are weighted for balance on the flexplate. Supposedly, you can't interchange and make the mistake because bolt pattern differs. Info differs somewhat on the years for the t350. Some say 69 to around 82 when they started phasing them out but some sources say they were still being used up to 89.

Besides needing to know whether you need a 153 tooth or a 168 tooth ring gear. You would buy the flexplate to match your motor and not the transmission. Speedway lists pt# 910-48362 as 86-94 153 tooth, 1 piece rear main for $23.99.
Pt# 910-48364 is the 168 tooth variety, same price

This is all very confusing.[S

There is probably an aftermarket flex plate made to suit your needs. I'd call the Summit Racing tech line and see what those guys tell you.

Found it[cl
Speedway motors has it just like Smallfoot said.
part number 910-48364,it is 168 tooth with dual bolt pattern.
Mine is the 10.75 converter
That will match my starter and fit my converter.
Thanks guys,I knew I could find answer here.

I must have had dumb luck, I swapped a TH400 out to a 700R-4 on my 64 C-10 that had a 327.... haven't had any problems.... hmmmmm or maybe I just don't know there is a problem

christcrusader13 said:

I must have had dumb luck, I swapped a TH400 out to a 700R-4 on my 64 C-10 that had a 327.... haven't had any problems.... hmmmmm or maybe I just don't know there is a problem

Click to expand...

The flex plate problems are generally motor problems in matching starters and flexplates(tho some changes were made to torque converter size also). When it's said that chevy motors are all widely interchangeable, there are exceptions.

i was thinking they had both tc patterns as i have pulled 700r4's and replaced with th 350's and 400's with no problems and the other way too. but i have been known to open mouth and stick foot in too.

And maybe some guys around these parts just lead charmed lives.