Hi everyone, my name is Alec, I am 18 and I am new to the forum but I figured I better join one in case I run into problems with my "new to me" truck. It is the first 4x4 vehicle I have ever owned. Had $2500 and came across this great deal and talked him down to $1000 from $1800. So overall I a stoked about the purchase. I am gunna give the low down below on the truck!

1982 GMC Jimmy
252,xxx miles I think.
350 5.7l V8 (Rebuilt 80k ago)
TH350 Tranny (Rebuilt 30k ago)
4x4
6 inch lift
Currently running 31's, I know it's lame but I should get my hands on some 35's or 37's before Friday.
Black on Black on Black

I know, I know, I will post pics as soon as I get it out of the shop, do routine check-up and tune-up, letting the mechanic check it out.

But I have some questions for some of yall? Bare with me I know some might be ridiculous.

1. Are they auto locking hubs or manual? Where the little ***** if you will are covered on mine, so I'm guessing auto?

2. The TH350 is a 3 speed correct? Or a 3 speed with overdive?

3. Previous owner said it could fit 37s no problem, but I would be very upset if I bought the tires and I had to trim, the body is in great condition!

4. To engage 4x4 I put the truck in Neutral, press the brake then slide the T-Case lever into 4High Range, then since I think they're auto(wish they were manual), I need to back up a bit before they engage?

Like I said sorry for the silly questions just looking to learn the right way.

Thanks I should have pics up by Wednesday the latest.

 

1. Are they auto locking hubs or manual? Where the little ***** if you will are covered on mine, so I'm guessing auto?

probably auto yes. but they did sell a flange end also which just leaves it locked full time. it has like 5 screws on it and says 4x4 on it like this then its a autohub



2. The TH350 is a 3 speed correct? Or a 3 speed with overdive?

th350 is just a 3 speed transmission. no over drive

3. Previous owner said it could fit 37s no problem, but I would be very upset if I bought the tires and I had to trim, the body is in great condition!

eh... thats really border line fitting. ive owned 3 k5 blazers with 6inch lifts and ran 38 12.50 tsl super swampers. with the 6inch lift those were super close. i could drive the truck but any turns over like 3mph or any bumps they would rub. my last k5 i bought was nice so i didnt wanna trim the fenders i put on a 2inch body lift and they cleared just fine. maybe you can get lucky and not rub with 37s but i dont know

4. To engage 4x4 I put the truck in Neutral, press the brake then slide the T-Case lever into 4High Range, then since I think they're auto(wish they were manual), I need to back up a bit before they engage?

if you have the manual lock outs then you would have to back up to engage. you dont always have to but it usually helps to ensure the pressure is off and they did slide in. thats to assume those autohubs even work. i been offroading a good 10 years and have seen those things fail and have a mind of their own. you can go buy a set of manual hubs for around a hundred and they basically bolt right on

Like I said sorry for the silly questions just looking to learn the right way.

Thanks I should have pics up by Wednesday the latest.

 

Ok thanks for the answers to my questions, and yes my hubs are covered with the 4x4 symbol, so it would be my best bet to just buy the manual locking hubs? and I think I'm going to settle with 35x12.5x15r for a decent price new.

Should have pics up hopefully by tomorrow but if not Wednesday for sure.

Quick question, since I have the auto hubs, do I just do the same process except I don't have to reverse? I will if I can, but do I have to with the autos?

 

Hi and welcome from Ontario,
i think there is a little confusion over the "auto hub" issue, i'm no expert but will tell you what i have.
Manual hubs have selector switch on the hub, you have to manually twist it to lock.
My 91 is automatic hubs for 4 x 4 operation, shift into 4 hi while moving (not too fast) and 4 wheel drive is engaged. To go into 4 Lo, you have to stop, put into neutral and shift up to 4 lo before putting tranny into drive.
To disengage 4 wheel drive auto hubs completely, stop and reverse vehicle approx 10 - 15' before travelling forward again.
This is procedure for my 91 Blazer with auto hubs and 4 gear auto tranny, your older Blazer will have a different t-case and maybe it's a full-time 4wd? meaning the hubs are always engaged even if the front shaft is not driving them. My grandfather's 75 Jimmy was like that, pigs on gas!!
Anyway, even my rig should be changed to manual hubs cuz the auto hubs usually wear out after awhile.
Check with a local club for some help, good luck.
Jim

Also, there is a bit of a job changing from auto to manual hubs.

 

you can leave them in there if they work. ive just seen to many times of trucks offroad getting stuck and them things not engaging or slamming in and out of engage and disengage. i just like knowing that i turned a dial and its locked no ifs ands or buts with the manual hubs you have to move a hair forward or backwards cause your basically meshing two gears together. if they hit each other they wont engage untill one gear hits the gap of the other gear to slide in. im not quite sure about the backing up autohub stuff ive never actually used a set i usually throw them out soon as i buy a truck with them

 

If you replace the auto hubs with manual style you will need to do some work inside the transfer case. Which is btw a NP203. Do a little research on the part time conversion for the 203.

The oiling system in the 203 relies on the movement from the front drive shaft to lubricate various points in the case.

where are those pictures?

 

An NP203 equipped truck would have originally come with solid splined pucks in the front hubs since it was a fulltime 4wd transfer case.

Assuming the transfer case was not swapped out for an NP203, it is much more likely that it is the NP208 which was the only stock option for the standard K5 in '82. The NP208 is a part-time 4wd transfer case. If you have a 2wd position on the floor shifter bezel, then you do not have the NP203. NP203 lever position options were HI-LOC, HI, Neutral, LO, & LO-LOC. No mention of 2- or 4-wheel.

With that said, Auto-locking hubs are famous for not working when you need them. The swap to quality manual hubs (Warn Premiums are worth the cost here) is a must if you find yourself in the sloppy stuff often.

If someone has swapped in an NP203 t-case & it hasn't been part-time converted, then the you'll find out quick if you install manual hubs. In HI or LO, the truck won't move with the front hubs unlocked.