well after all the info from a lot of helpful people my plan is to swap the 5 spd in my 1990 sidekick to a auto and go with 31 tires and the 2 inch sl and 3 inch bl combo kit, plan to build my own bumpers and mount a winch upfront, want to snorkel it and add down support to the rolebar(mainly for looks) 2 1/4 exhaust from double down pipes to back of unit with dynomax muffler aaaaaand myand  question is, do i need to change computer to swap in auto trans and is it a fairly easy swap?

You can use the 4 speed Volvo transmission instead of the Geo/Suzuki one.  It is a mechanical so you don't need the computer bits.

As I understand it the early 3 speed auto's are not computer controlled You will however need all the accessories, Kick down cable and vacuum ports on the engine etc.

The 4 speed Auto is computer controlled. You can get a controller from http://awshifting.com however it only gives you manual control of the transmission.

The Transmissions Suzuki uses are Asian Warner made and these transmissions have been put in a ton of cars and trucks. They made a non computer 4 speed for Volvo which will fit as I understand it if you change the bell housing. I am not 100% sure about the other end where the T case attaches.

I found this link: http://en.wikipedia.org/wiki/Toyota_A_transmission  According to this page They put a Asian Warner 4 speed transmission  "A43DL" into 1982-1985 Landcruisers This is suppose to be the same as the "A43DE" which came in 92 and up Sidekicks. It is not computer controlled and coming from a Landcruiser it will already have a transfer case attached to it. Could be an interesting swap.

The 3 speed auto is not a computer controlled tranny.  So your manual tranny ECM will work....it may run a little odd at times, but it shouldn't be bad enough to cause any driveability issues.

thanks guys,will start hunting for a 3 spd auto and get this project underway, my 13 yr old is pulling at my coat tail to get this going, pretty excited to get it on the road!

final drive gears are different from auto to manual as well.  I was going to buy and auto and swap in a 5spd until i found that out, but i'm not sure if it will be as bad the other way around.

the guys on the forum are saying that the auto has 4.60 gears and the 5 spd has 5.12 gears, i want to switch to a auto to run 31 s and hopefully keep the same tcase and diff.gears to have it run close to stock rpm on/off road hg/low range.sounds like it should work well, need a auto trans and all hardware for my sk if anyone has this close to manitoba/northdakota border?

final drive gears are different from auto to manual as well.  I was going to buy and auto and swap in a 5spd until i found that out, but I'm not sure if it will be as bad the other way around.

I was under that impression also, which is one of the major reasons I was considering a auto swap into lil Suzy. I looked it up yesterday and both automatics and the 5 speed all have high gear out puts of 1.0: 1. Of course the over drives vary between the 4 and 5 speeds but the only reason the autos have lower R&P gears is because of the torque multiplication of the slush box. Still not a bad reason to switch but not as good as I had hoped.