Re: So....I put the wrong tranny in my Zook?!
86-88 5th gear ratio is 0.795:1
88.5+ 5th gear ratio is 0.865:1
In other words, you'll be turning fewer RPMs in 5th gear with an early transmission than with a later transmission. The difference is worth about 300rpm at the same highway speed.
I don't know which transfer case you have, but assuming you have the stock one with a 1.41:1 high range and the stock 26 inch tall tires with those 4.10 gears, you'll be turning 3267RPM at 55mph with the early transmission, or 3554RPM at 55mph with the late transmission.
-- Geoff Beasley