The rear has 26 spline, the front has 22 splines. The Spartan Locker uses your original side gears, (thats the ones the axles fit in) so it can be installed in either one.It is a very simple install. Part number for your 1988 is SL SUZSAM I think. You can find them all over the internet. Trail Tough, Ebay, Rocky. They cost around $220.00 most places.
I welded my rear and bought a Spartan for front.
Wade