How to tell different Transfer Cases???

[js9234]

I have an 81 w/granny 4 spd and was wondering how to tell what type of Transfer Case I had. I just bought the truck and not sure what all has been done to it. I really can't tell if it is alluminum or not.

[Snuke87chevy]

There should be a red and silver tag on your t-case that shows a serial number and the model of your t-case.  An aluminum one would have the model NP-208 and a cast iron one would be an NP-205.

[js9234]

So which is the better of them?

[Blazin]

The NP 205 is more rugged but the 208 has a lower low range gear. Depends on what you are using the truck for. Heavy four wheelin and mud running the 205 would stand a better chance of survival. For all around purposes the 208 is a very capable unit. I will have to say I have never broken a 205 or a 203, but I have granaded a several 208s. My 86 K20 has a 208 and I have had good luck with it I two alot of cars on my trailer and plow 45 driveways every storm going on 4 years now and the only problem I have had with it is after new clutch, motor mounts and a bunch of other crap it would pop out of 4 hi go half way in between 2 wheel and 4 wheel. I adjusted the linkage rod and have never had any other trouble with it. The one in my 81 Blazer has survived some pretty serious wheelin but it has developed a large crack in the rear half of the housing.