I would ask the PlanetIsuzu guys. AFAIK, it depends on the spline count. I pulled a pair of WARN manual hubs off a 90 Trooper and have yet to see if they fit my Trooper. I think they will since my Trooper is a 91 and the donor vehicle was a 90, but I suppose there is still a chance. IIRC, the 1st of the 1st gen Troopers had a different spline count than the later 1st gens. The WARNs I got are nice. I hope they fit.
Bart