once and for all T-CASE info

[BurnoutNova]

ok, ive always thought np-203 is the all wheel drive t-case from 73-up, and the 205 is the partial time 4x4 unit, and the rockwell 221 is a 3/4 ton model.

thats all i know.

FILL ME IN!

thanks
zach

[454_72_4X4]

203 is chain drive. (full time 4WD)
205 is gear drive. (4lo, 2hi, 4hi) IMO the only T-case to have.

Only seen one rockwell so I don't know much about it.

[MJN]

205 gear drive part time case, good strong dependible. NP201 is another t case same as the 205 but makes the 205 look tiny, it's big. The rockwell, same as a 205, came in 1/2 tons as well, came in trucks before the 205 was offered, gear driven, good strong case just hard to find parts for, also about the same size as a 205.

[454_72_4X4]

Isn't the Rockwell 221 the one that the rear output shaft comes out down low? Or am I thinking about a different one?

My dad bought a 67-8? 3/4 ton a few years back that has a transfer case with a lower rear output shaft. Just wondering if this is the Rockwell 221.

[1969 GMC]

NP203= full time 4x4, mostly aluminum, chain drive, 200 lbs (no thanks)

NP205= part time 4x4, came in every major brand of 4x4 truck at one time or another, cast iron, ~135 lbs, very popular & strong

T-221= part time 4x4, cast iron, came in chevy trucks from '60-'69, smaller than NP205 but about as strong, and yes it does have low outputs. Bigger brother the T223 was used in some older military trucks.

NP208, NP241= aluminum chain drive part time cases that were introduced in the '80s. I say no thanks.

NP200, NP201, NP202= part time, cast iron, very heavy, resemble the NP205 but are much older, and larger too. these came in some Dodge and International trucks, such as the M37 Powerwagon.

Dana 18, 20= cast iron part time cases that came in some jeeps, scouts, and selected first gen K5 blazers and early GM trucks, usually mated to 3 speed tranny.

Dana 300= cast iron part time, very valuable to offroading crowd, came in '81-'86(i think) CJ jeeps, and 1980 only Scout IIs.

if anyone can add to this, or make corrections, feel free

[NAPCO ken]

the T-221's bearings are tiny compared to 205's...thus they are not nearly as strong as 205s. the 205 weighs about double that of a 221...and you say it is as strong??

[Southern Rebel]

I'm a new blazer owner of a 1970 K5/250 I6/3-speed. My first 4x4, how do you figure out which transfer case you have?

[bouncytruck]

NP203 is mostly cast iron. It does have a big aluminum section and they are extremely heavy. Part time kits are available and many people use them in conjunction with the 205 to create a "doubler" for crawling.

Southern Rebel, I would guess that your truck has a Dana20.

Here's some pics of my NP203 when I pulled my transmission:

http://info.imageink.com/chris/image026.jpg

http://info.imageink.com/chris/image028.jpg

[DennyB]

Is this info correct?

[bouncytruck]

Looks right to me. CK5 also lists the specs for Blazers.

[Southern Rebel]

I just checked the specs on CK5 site and it lists 2 transfer case for the 1970 Blazer 1. NP 205 (1.96:1 Low Range) & 2. Dana 20 (2.03:1), How do you determine which one?

[1969 GMC]

Southern Rebel, the easiest way I know to tell the difference would be to get under the truck and look. For reference, here is a pic of a NP205, even though its out, this would be the rear end of it. If it doesn't look like this...then it is a dana 20.

[1969 GMC]

Napcoken, I just took my T221 out and am swapping in a NP205, because the bearings blew. The bearings on the input shaft look to be about the same size...

[Blazer1970]

Originally posted by Southern Rebel
I just checked the specs on CK5 site and it lists 2 transfer case for the 1970 Blazer 1. NP 205 (1.96:1 Low Range) & 2. Dana 20 (2.03:1), How do you determine which one?

The Dana 20 has a "U" shaped shift pattern. The 205 shifter just moves front to back with the selections being 4HI, 2HI, neutral, 4LOW from the seat to the dash. Your Blazer should have come with a Dana 20.

[bouncytruck]

I think the 6 cyl rigs in 1970 were all backed by the Dana 20. I belive the 307/3speed rigs were too. If it is stock, yours should be the Dana 20. If your rig is like mine, someone could have swapped out the original 307/3 speed/Dana 20 for 350/TH350/NP203 combo. Those NP203's are heavy!!!!

[1969 GMC]

someone even posted on here a while ago that they had a blazer with a 4 speed and dana 20, stock. imagine finding a replacement adaptor for that combo...

[Blazer1970]

Originally posted by 1969 GMC
someone even posted on here a while ago that they had a blazer with a 4 speed and dana 20, stock. imagine finding a replacement adaptor for that combo...

They made a lot of them that way. There is really no reason to worry about finding an adapter though, since you can find a 465/205 combo really easily, and it swaps right in. Driveshafts will even work.