okay i was at the junkyard yesterday.I want to have fulltime 4x4 in my 89 that came with a 231(2h,4h,n.4lo)i have seen 2 other t-cases besides this one.one has,but don't quote me(2h,4high lock,4h,4lo)the other had(2hi,4full time,4hi and 4lo)whats the diff?