Welcome, you sound like someone I spoke to on the phone?
u-joints should not have any play in them.
I'd avoid the 16% unit like the plaque! ....others may disagree?
A member here has an excellent QT info site, http://jubileejeeps.org/quadratrac/index.htm
If you have lockouts on the front already, there is a chance it could already have a milemarker conv. in it.
Did it have ATF in the case when you checked it?
If it's working good, I'd just replace the chain. If not, I have 2 of them collecting dust I'll sell CHEAP!
(As in cheaper than buying a chain)