Not to sound harsh, but if you have to ask these questions, an antique vehicle the the "owner" cant get running with a $20 part, 20 minute fix (did you know that?) with a leaky box on the back full of other things that will be or are broken is not a wise purchase.
Unless you're homeless, then it should be about the cheapest rolling shelter you can buy short of a tent and a wheelbarrow and generally the 360/727 drivetrain is reliable, provided it's actually in good operational condition.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5โ turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold