The only auto that will bolt up to the m18 is the one from behind a m13. That particular auto will be your weakest link.
If your jimny is already a g13 then the g16B (coilpack = no wiring needed) will bolt up to a vit AW4 auto. Or even a j20a, if you want moar pow, with the AW4 will be bomb proof, possibly cheaper and less heartache in the long run.
G16 will use jimny or RB30 vl commie mounts + some fab (if you don't buy a mostly useless adapter kit). J20a will need some fabbed mounts.
M series will need ...oh wait.. theres a thread all about this
http://www.auszookers.com/forum/viewtopic.php?f=17&t=30308