Just wondering what years on these will work best to swap one in where a TH400 is now, in an '85 C20 Suburban 6.2L? 400 is bad anyways, figured I'd start hitting the self-serve junkyards for a donor truck I could pull all the bits out of. There a website that gives a good summary of the changes in these transmissions from year to year? I see a post further down with all the RPO codes to help ID things when I do find a potential donor.