1972 K20 rear end question

[Retro]

Hey guys, so I'm a fairly smart guy, but when it comes to rear diffs...I don't know squat.

I have an Eaton open diff in the rear of my 1972 K20. I've been told if I'm interested in a locking/posi/etc rear diff, I should consider a Dana 60. I have pretty tall gears (4.56) in the Eaton, I'd like something a little more road friendly - 4.11 or 3.86 maybe?

So, what do I look for? What year range with what gears, etc.? What are the details I need to know to buy the right thing?

Thanks in advance for any guidance! I appreciate it.

-Retro