Denny, you're incorrect. The HO series Eaton rear ends were used clear up to 1972 in 3/4 and 1 ton applications at least, and they did come in 4.11's. There is a one year only 3.90 (1968, I think), which I believe Art Hauser used to make his limited run of reproduction 3.90 gear sets some years ago. I put 4.11's in my 55.1 Chevy NAPCO. One came from a 62 Chevy and the other from a 66 Chevy. Direct bolt in. You can see more information here on Rob English's 4.11 rear end swap from quite a few years ago. Since this article was written several other part numbers have been verified and a whole bunch of guys have done this swap.
http://www.oldgmctrucks.com/page0276.html
