Need help on a 1979 Jimmy

[79bluebeast]

i own a 79 Immy 350/ 350?/ np 203, it has a 4" lift i believe from rancho it has rancho shock absorbers all around. and a decent set of 33's from cooper. it has a rear main leak and i don't have the funds to do a rebuild so i was wondering if i could just drop the rear main and replace the seal that way without having to unbolt the tranny? the tranny is from what it looks like form the modular a th350 but it has 4 forward gears in it and my gear selector only shows D 2 1 I was wondering if that is normal for that year or if it has a different tranny from a different year all my friends told me that it should only have three speeds. The shift points are: 1; 0-24, 2; 24 -36, 3; 36-50, 4; 50- on up, top'd it at about 115 from what a gps said. it hooks up to the carb the same and the vacum line hooks up right, so i just want a more educated oppinion on what it might be. I also wanted to know if anyone in the NE area might know the junk price on a front drive shaft, its currently sitting in the back of the truck right now in three or four parts and its burning up my transfercase. thanks

 

[tRustyK5]

Snap a pic of the tranny pan, that'll tell you if it's a TH350 or a 700R4. 700R4 has a square pan, TH350 has a square pan with one corner knocked off, and a TH400 is sorta shaped like TX (if you're drunk and failed geography)

Rene

 

[79bluebeast]

its a square with the corner cut off, nobody i talked to has ever heard of one having 4 forward gears in it.

 

[onetonjimmy]

sounds like you got a th-350 with a lock up torque convertor

 

[79bluebeast]

sounds like you got a th-350 with a lock up torque convertor

i dont have a computer on it though. i dont know, as long as it works im not worried about it, i only have issues with it in the winter.

 

[Hogback Fabrication]

i dont have a computer on it though. i dont know, as long as it works im not worried about it, i only have issues with it in the winter.

Lockup torque converter doesn't need a computer, you have a TH350 which is 3 forward gears that fourth "shift" you're feeling is the torque converter locking up which lowers the RPM.

So you're running your fulltime 4WD truck without a front driveshaft, is the t-case in 4-hi or 4-hi-loc?

 

[79bluebeast]

Lockup torque converter doesn't need a computer, you have a TH350 which is 3 forward gears that fourth "shift" you're feeling is the torque converter locking up which lowers the RPM.

So you're running your fulltime 4WD truck without a front driveshaft, is the t-case in 4-hi or 4-hi-loc?

its just it high, my lok dosent work. it hasnt worked since i bought it. it goes in lok in park or nuteral but as soon as i start going my lok light goes out and the shifter moves out of gear.But im not really complaining i get like 17-19 mpg in town. i can put my foot in it all day around town and not use any gas, and yes the gas guage does work in it.