Sounds like you need the newer version used on some 638 and all 880 blocks that I have seen. GM Goodwrench TBIs were often 880 blocks. The 1-ton replacement TBI engine I had in my G20 was an 880 block with roller provisions and used the 2nd design aka ZZ3/ZZ4 retainer plate.Yeah, mine is labelled "Older Design". I took measurements and, hopefully, I'll find the correct spacing. IIRC the one I have is ~3.3625", I need one a little smaller.