Who makes the adaptor for the flex plate and what do they cost? Thanks

 

just order a SFI approved Flexplate from TCI..... here is the part number.... 890-399753...$214, it has bolt holes for the TH350 converter as well as the TH400 converter.... and is actually the same for the 4l60e's as well. just make sure the convertor you go with has an extension to fit into the rear of the crank....