Identify Transmission and Transfer Case

[sgr60]

I'm wondering how I can ID my tranny and transfer case on my '84 K20.

The tranny is a 4-speed (L,1,2,3) manual, that's all I know.

I've looked around some, but I can't find a clear reference for how to ID both of them. I want to change the fluids, but I want to make sure I use the right fluid for what I've got.

Thanks.

[mattybilt79]

Trans should be an sm465 and t-case np205 but could be a 208 if its an aluminum case.

[sgr60]

So the way to tell the transfer case between the 205 and 208 is only the 208 has an aluminum housing?

Any other possibility on the transmission- or that's the only one it could be?

[sgr60]

I've just read through the GM service manual and I see that there are three manual transmission options for the 1984 year:
3-speed 76mm
4-speed 89mm
4-speed 117mm

From what I can tell, the 89mm has overdrive - which calls for different transmission fluid than the others - so I want to make sure which option I have. How would you know if a manual tranny had overdrive? That confuses me...

Also, the manual doesn't seem to reference the shift pattern that I have L-3, all it talks about is 1-4. More confused that when I started...

[Ziegelsteinfaust]

I would say he has a 208 case since it is a K20. The 30's got the good stuff unless it was special order or part of a package.

[donut]

As far as telling if it had OD. Start the truck, put it in 1st gear and go. Does it sound like it's taching out before you hit 25 mph? Do pedestrians pass you in first? Normal driving, can you start from a stop in 2nd gear without having to really feather the gas and clutch?

This would indicate "granny low" and thus 3rd gear would be 1:1. If you have to start in 1st and you don't hit 4th until about 50 mph (without "winding" on it)...

Transfer case, you may have to post a pic. 208 not pictured here. http://www.chuckschevytruckpages.com/drivetrains.html

[sgr60]

For the T-Case, I found a label on it - it's a 208. So I've got that covered.

For the tranny, when you say start it in 1st, do you mean L? I don't typically use that - I normally start in what's labeled 1st on the shifter, but is actually 2nd, after L. It goes L-1-2-3. My assumption based on what you said is that I don't have OD, so it's the 4-speed 117mm. Would that be the sm465?

[JIMs70GMC]

I just bought a SM465/NP205 combo from a guy, the truck was a 84 K20. I believe the NP208's have a slip joint tail shaft. The 205 got the slip joint tail shaft in 85 or 86. I think the 89 mm tranny is the NP833 or something like that.

yes the 117 mm is the SM465.

[andrewmp6]

Or take a picture of the t case from the rear side and post it we can id it.

[mattybilt79]

Your trans should be a sm 465. The other trans referenced are 2wd. And you found your I.d. tag for your 208. 465 trans should have PTO/inspection covers on both sides of transmission if I remember correctly. If your still not sure google sm465 i.d.

[Your41Plague12]

It's definitely a SM465 with that shift pattern.