If you can't drop the coin for a selectable locker like an ARB or a OEM E-Locker, a limited slip is decent option in the front for a full time 4wd vehicle. I know a few Rover owners that run Detroit TruTracs in the front. I don't think that they on par with a true locker, but they beat an open diff unless you stick to the pavement.
The true trac would be best for a front LSD. If you don't want to drop the coin for one, a clutch type LSD from an 86 - 92 Supra will work well, is cheap to obtain, and drops right into the front of your cruiser. About the only mod I recall performing was grinding a smidge off the inner axle shaft as the splines in the LSD were a bit more shallow. The 93 - 97 Supra with 8" diff has a true trac type helical LSD, I would assume it would drop in...? It will be more money.
I would not put a non selectable locker in the front of an 80, it will handle oddly in slippery conditions. You may not have snow and ice to deal with but you do have lots of wet roads year round, off road the truck will have a tendency under steer.
I agree with Raven if we're talking about a DD and it appears we are. If you insist (and it seems like you've already made up your mind) then don't let others drive the truck until they are completely comfortable with the bizarre handling you will have with a LSD front.
I would only go with a selectable locker in the front... IMO LSD´s and auto lockers are not safe nor fun on a fulltime vehicle ... they are OK for the rear but not the front ... go ARB or wait for Electracs or cable lockers ... who knows when...