Somebody mentioned the axle ratio perhaps being different. There is no indication on the door tag as to what axle I have, although there is a sticker which cautions about a limited slip differential. Is there a tag anywhere identifying the axle? Failing finding a tag, the only way I'm aware of to determine the ratio is to jack up the read end and start turning the wheel(s), and count driveshaft revolutions. This should also answer about the limited slip differential.

I believe the transmission is a three speed. The shift lever is marked "P-R-N-D-2-L" . In my mind that says 3 speed. When they went to a 4 speed, was fourth an overdrive or just a straight drive with closer ratios?

Since this Montero (assuming that I can get it running) will be going onto an island in Maine, with only about 20 miles of road, of which only a third is paved, the overdrive would serve no real purpose, though the closer ratio might be a benefit.