its me again. well did some slight mods and like i said i bought it used and now the tranny has lost reverse and 4-0d so i was wondering if the yukon tranny's will bolt up on the 4.3 with out any mods...or if there are mods r they big ones??? and is the yukon tranny better or worse?

 

If it is a 4L60E, it is a direct drop in (provided they are both of like drivetrain configurations - both 2wd or both 4wd). If the Yukon had the heavier drivetrain (4L80E), then things won't be a direct bolt in.