how do I find a flexplate for my BIG BLOCK

[MEGALADON]

I pulled a 454 and 400 trans from a 78 GMC, I put the 454 in my 82 GMC,
the flex plate would not line up with the 350 trans, so I grinded the hole larger
and noticed a vibe, I am getting ready to stick my 700R-4 in, how do I know what flex plate to install so the bolt pattern lines up with the flex plate???
I gues the original flexplate was only for the 400 trans!! But i'm no specialist.

Will this be one of those trial and error problems for me, I'm pretty sure a flexplate is out their, that would work.

For what I understand, the motor is externaly balanced

 

[gauder]

You need an externally balanced flexplate for a 454, get one with a dual bolt pattern for converters (10.75" and 11.50") and you should be fine.

 

[mudjunkie 82]

contact Summit racing for one.

 

[sweetk30]

http://www.northernautoparts.com/ProductModelDetail.cfm?ProductModelId=2521

good prices and parts.