1st time posting, tranny-tcase questions

[894runn'n]

so i have an 89 4runner with the 3.0 v6 with R150f tranny(so my vin says) and my rear main seal is leaking pretty bad, so me and a buddy took on the task of dropping the tranny and pulling the clutch and flywheel to get to the seal. we replaced that no problem, but i got to thinking...since i got this out this would be a great time to add another tcase. so i got on this website, read a bunch of forums and found out that my vehicle should have come factory with a R150F tranny and a forward shift chain driven t-case,(please correct me if im wrong). but when we pulled it i notice that my T-case is a top shift not a forward shift. I pressure washed and de-greased my tranny and tcase hoping to find some markings that would tell me what I was dealing with, and the only thing i found was a code on the side of the tcase(90101242). but when i searched the web i didnt find anything for what that represents. I want to order MC's dual transfer case adapter kit and 4.70:1 gear set for my rearmost tcase. but being as i am new to the crawling world I wanted to check and make sure i get some good info to help me order the right stuff the first time. My spare tcase that i have is out of a 1985 4cyl and is a top shift 21 spline. I appreciate an helpful advice that can be sent me way, and im sure this might be a stupid question, but like i said, im new to this and just trying to learn as much as i can. thanks!

[Cyberman]

I've been there.  91 v6 extended cab here.  First off in order to put a gear driven case in, you'll need an adapter between the transmission and the transfer case. The adapter and the input shaft needs to be 23 spline.  Most people don't use the chain driven case.  The way I started out was to put 4.7 23 spline gears in a top shift case, with the v6 adapter.  If you do just the single case, you won't have to modify the drive shafts.  I ran this way for about 2+ years.  Where I wheel, I don't have long stretches between trails, so the lower gears didn't slow me down too much.

Recently, I went with duals, which requires another top shift case, a crossmember and a dual case adapter.  The drive shafts would need to be modified at this point.  I have a two-piece rear shaft, and just got the intermediate shaft shortened 7 3/4".  The front was lenthened as well.  Doing it the way I did allowed me to gradually get where I wanted, without spending all the money at once.

If you want more info, feel free to send me a PM.

Sent from my DROID RAZR using Tapatalk 2

[Rocksurfer]

to Marland, looks like you are in good hands to figure it out.