Gm 203 transfer case identification

[hardin.chris123]

I got a 1978 scottsdale k20 with a messed up transfer case. i have 2 other 203s and I know some was a all time four wheel drive. Mine has 2 high 2 low 4 high and 4low I would like to have same one but can't find a identification site like you can with heads and blocks. If anyone could find me one I would appreciate it

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[hatzie]

Every NP203 was full time 4WD originally.  Part time NP203 xfer cases have a locker installed by an owner, or at their request, in place of the diff in the transfer case.
I've had one in a 78 W200 Dodge Power Wagon and it was the original xfer case in my 76 K20.  I miss the full time 4wd in my Power Wagon and the 76 would still have the 203 if it wasn't so badly damaged by the PO slamming it into a big chunk of hard stuff.

[hardin.chris123]

Alright I appreciate it like mine was messed up cause it was drag raced with still being the k20 runing low 6s if not high 7s in 1/8 mile and was run in 4high and,it's just all messed up now

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[hatzie]

Since the Prior Owner installed a part time kit your front hubs should have the slugs replaced by manual locking hubs.
Sell the NP203 to a hardcore wheeler.  They'll use the range box as a low range doubler...  Or keep the range box for a project.  Get a decent condition NP208 or RH drop GM NP241 (if you can find a 241) and install it.

Folks claim the NP208 is a "weak" transfer case because of the silent chain drive.  I have a stock NP208 in my M1008 behind a TH400 and the same in my 76 K20 behind an NV4500.  In the early 1990's I plowed snow for 3 seasons with a badly abused NP208 in a 1986 F250 behind a 460 with a C6 auto.  The only thing I ever broke on that truck was the yoke ears on the RH axle shaft in the badly badly badly abused Ford IFS Dana 44.

RH drop limits the available common transfer cases.  NP203AWD, NP205, NP208, & NP241...
The NP203 & NP205 are heavy, expensive, harder to find and have the worst low range of the possible cases.  The NP241 RH drop is rare and usually priced accordingly.
Low range on the NP208 is 2.69:1, the NP203 was only 1.96:1, and the NP205 is the same 1.96:1 as the NP203.  You can install your NP203 range box on an NP205 for 3.92:1 low range but that's serious $$$.  The RH drop 1989-1991 RV series NP241C is hard to find.  The .03:1 difference of the 2.72:1 low range isn't significantly better than the more common NP208.

[Engineer]

I like the idea of swapping in a NP205. All gear, no chain to slack out (usually not a problem if the case is a part time 4x4) but gears are definitely superior. Since 205s were OEM to our trucks you have parts commonality and no aftermarket adapter hocus pocus. 205s are still easy to find especially if you are looking at switching to a 4-speed.

The 1.96 low range could be a problem if you are into rock crawling. In my case I was sled pulling and the 1.96 low was perfect.

[hatzie]

The 205 gets exciting when you want to bolt it to transmissions like the NV4500 in my 76.  Exciting = $$$.
Gears sound nice but the downside is they're popular which translates to expensive, a lot of unnecessary rotating mass sucking up HP, and the cast iron case is dead weight too.   

The New Process/Venture 203, 205, 208, 233, 241, 261, & 271 commonly burn up bearings because they are run low on lube. The same goes for the Borg Warner 13xx & 14xx cases.  Leaks not being tended to from bad seals or bashing them on big heavy things are the leading reason they are low on fluid.  The slagged 208 that came in my F250 plow truck leaked through a sizeable crack from bashing against something...  If it hadn't had a cracked case the bearing races had spun in the case too so the case was shot.  I installed a well used but solid 208, a home brew torque brace, and a bash plate before she got license plates.  I then proceeded to beat the crap out of it plowing for four years.

Everything but the 205 & 203 commonly crack cases when they are run with no torque brace...  Personally I've added a torque brace to all four of my 4x4 trucks... One 67 Dodge, Two Fords 72 & RIP86, and Two Chevys 76 & 86. Cheap low tech insurance.

If you'll be running larger than 33" tires get another 203 or a 205 and add a torque brace.  Otherwise get what's cheap, working OK, and easy to find.  Install a torque brace when you put it in.