1990 - removed two of four spider gears from front differential
- wheelbase increased an inch or two (inorder to improve the ride)
- added FI (fuel injection) to 1.3L engine, increased horsepower to 66
- tranny and tranfer case bearings changed to the sealed design
1990 is correct for the first year for EFI.
Suzuki actually removed 2 of the 4 spider gears in the front carrier in 88.5s (although 88.5s were generally a mix and match of parts....so some had 2 spider gear front carriers and others had the older 4 gear style).
The wheelbase never changed....it is 79.9"....86-95 samurais. They did change the rate of the rear springs at some point though, to improve the ride (I think it was in 88.5).
this link should give you all the info you need.....
http://en.wikipedia.org/wiki/Suzuki_Jimny
Wikipedia is generally a pretty good source of accurate info. But it isn't always true. For example, they say, "A new 1.3 4-cylinder engine with throttle-body fuel injection was introduced with 66 hp (49 kW) in September 1991." Which is obviously wrong. The 1990 model year samurais were the first ones with throttle body EFI.