Front diffs give you a lot of options since you don't normally use them. My Jeep has a limited slip diff in the front (name skips me atm) a clutch type. I would never use a clutch type lsd in the simply because I don't want to replace the clutch discs on an annual basis. But, I had my local Jeep shop set it up, and I'm not an expert on lsd's but they can make them nearly as tight as a locker.
But anyway, if I wasn't going to go with a selectable locker in the truck (and I'm not, funds just aren't and won';t be there for a while) I'd go with the best limited slip unit made for my vehicle. With the exception of my Jeep (not a stock unit), normally you won't notice anything on the road and it will help a lot offroad.
Someone is probably going to bring up "okie posi". Application of the brakes while under power causing an open diff to apply power to both side equally. Works on older non computer controlled vehicles. Tried it on the Jeep once, cost me just under a grand in parts to fix what broke.