Compatible with what and in what respect?
If this relates to interchangeability of parts, Suzuki has a way of refreshing on a three year cycle, so for the most part 89, 90 & 91 model years will have interchangeable parts, but this is not a hard and fast rule, to cite two admittedly extreme examples, there is a relatively rare '89 Sidekick with a 1.3 engine that has a number of parts that are unique to it, and there is also at least one part on that same '89 Sidekick that was still in use on US market vehicles as late as 2003.