I replaced the rear end in my 49' 3600 with the Dana 60 out of a 69' F250. I had to weld spring perches which was simple enough and have the drive shaft shortened with a yoke welded on to mate up to it. It has 3.73 gearing. I have a 235 with the stock 4 speed and I can cruise 55 at 2500 RPM.

1949 Chevy 3600
1975 W-25 Hurst Olds
1970 GMC 1/2 ton Fleetside
2010 Chevy Silverado