How do i identify what transfer case i have?

[flywise]

1988 Suburban,
i also have another transfer case in my shed that came with the Suburban when i traded for it.

[El Forajido]

Chilton book?

[Brooks]

NP241C

Starting in about 1987, the New Process 231/241 series transfer case became standard in Jeep, Dodge, and Chevrolet applications. These transfer cases are part time 4WD (Shift positions 4HI - 2HI - N - 4L). They have a relatively thin aluminum housing. They are 1:1 direct drive in high range, and use planetary reduction gears for low range with a ratio of 2.72:1 They use chain drive for the front output. The NP241 was typically used in V8 applications.

Exact identification:

These New Process cases have a circular plate, about 2" in dia., on the rear of the case, in the center. Full identification info for the case is on this plate Bolt Pattern:
Jeep, Dodge and Chevy versions all use a 6 bolt circular bolt pattern. This pattern is NOT symmetrical and will only bolt up one way. You can typically bolt a Jeep unit to a Dodge transmission and vice versa, however Chevrolet units are NOT cross compatible: While GM uses the same 6 bolt patter, they have it rotate approximately 90 degrees from that used by jeep dodge.

In all of these 6 bolt applications the Klune-V Extreme Underdrive will bolt up to these transfer cases directly with adapters necessary. Some may require a spacer.

Slip-Yoke Eliminator
All of these units we have seen have been equipped with a slip-yoke rear output. Slip-Yoke Eliminator kits are available for most of these transfer cases

GM New Process 241 Transfer Case
In 1988, GM began using the NP241 transfer cases. Most of these units will be right hand drop, but Chevy also used a few left hand drop applications. The Chevy NP241 is supplied with a 27 spline female input or a 32 spline female input. With a T350, 4L60E or 700R4 tranny, it will be 27 spline. With a T400 or 4L80E trans or 5 speed, it will be 32 spline.

[BETTERLUCKYTHANGOOD]

Look on the back side of the case there will be a round tag screwed to the case. It will have the unit number on it.

[flywise]

Great info guys.....thank you