your rear diff is an 8" and the front is a 7.5" ifs diff. 4.88 was stock gears for v6 4runners that came with 31" tires from 1992 on i believe. its a bolt in swap.

87 4runner 33" bfg mt's no lift. dubbed the marine by my frinds. dead as of august 14 2005. 84 ex cab p/u 33"a/t, 3" suspension+3"bodylift, thorley header and 2.25xhaust, downey midrange cam+rocker set, very milled head! NO RUST!