PTL - I did the aforementioned Dana 60 out of an '87 Dodge 2500 pickup for my '59 Apache 3600 (basically the same truck as yours). 3:55 gears, limited slip, as close to bolt in as you can get. The rear is about 2 1/2" wider, and the wheels clear with no problem...the stance actually looks a little more badass now

. The most involved task was widening the spring perches, which I easily accomplished in about 2 hours with my 120V mig welder, some scrap steel and a grinder. I bought new U bolts, which you should do anyway. A spring shop bent them up for I think $25, including the bolts. I needed an adaptor for the brake line (1/4 to 3/16, it cost $1), and I had to have the drive shaft shortened 1 1/2", which cost $125. Lastly, I also had to get a new yoke for the U joint, which was about $35 from
www.actionmachine.com. If you have all the parts in hand, and the rear end it painted, prepped, and ready to go (the most time consuming part of the job), it should take you 2-3 hours at the most.
WELL WORTH IT!!! The truck is actually now drivable on the highway...it'll hold 70 all day long without breaking a sweat.
Good luck.
Chris
Once you get the rear end prepped, it's a pretty easy job.