There may be something about the perches that makes it "One year only"?? The pumpkin, posi and gear sets are 67-70.
Contacted the owner. He said there are 3 different rear ends. one is 3:07 and the other a 3:42. third has no idea.
I'd think those would be good for '66-'68 Wildcats and Electras, but not Rivs. I've sold mine for a bit cheaper and many ask for more $. Some get excited about the 3.42 sets.