What engines will fit what trans???
Will either the 1.8 or 2.5 fit the 1.6 trans?  If not are the transfer cases different also?
Here's what I know:
1.3 8-valve (Samurai / Swift) | Samurai Transmission (early and late model)
1.3 16-valve (Swift GT) | Samurai Transmission (early and late model)
1.6 8-valve and 16 valve | Sidekick Transmission (manual and auto)
1.8 16 valve (Sidkick Sport / esteem) | Sidekick Transmission (manual and auto)
2.0 16-valve (Vitara / Aerio) | Sidekick Transmission (manual and auto)
2.5 and 2.7 V6 (GV and XL.7) | Vitara transmission (manual or auto) (2.7 transmission will not fit Sidekick t-case.)
1.6 8-valve and 16-valve Sidekick (manual and auto) 2.5 liter Vitara (auto) will fit the Sidekick t-case and the crawler gear sets. 2.7 Liter XL.7 and 2.5 Manual is different. (2.5 manual's shaft is too long. 2.7 uses different output shaft)
So, there is a lot of mixing and matching that can be done to get the ultimate powertrain combo for your Suzuki... Good Luck
HTH -Eric