NP231 Junkyard Upgrades

I've read of the 231 transfer case being used in other vehicles, some of which had a 6-pinion planetary and possibly a 1.25" chain. Anybody know of ways to upgrade out 231 transfer cases using junkyard parts or what vehicles to get parts out of?

I used a wide chain and gears from a 233C (chevy, electrically shifted, maybe from an S-10). I think there are other models that have the wide chain.

This parts list shows the P/N for the two types of 6 pinion planetaries. Might be cheaper to buy the part you need rather than try and harvest from

http://www.southwestgear.com/product_pages/np231_gear.htm

Knowing that the OE part number for the 94 and up 6 pinion is 17869 just look through the cases on this site and find the ones that use the same PN. Do the same for the 94 and down if that's what you have.

http://www.tbtrans.com/transfer_case.htm

That pn seems to be used in a lot of cases. The 94 & down not so much though.

You could probably do the same thing for the P/N's of the wide chain and gears. Ideally one donor case would provide all the parts.


(here's another parts list but not as complete as TBTrans)
http://www.drivetrain.com/parts_cat...placements_and_parts/transfer_case_parts.html


you've probably read this one from Madxj:
http://www.madxj.com/MADXJ/technical/technicalfiles/JAtCaseUpgrade/tCaseUpgrade.htm

see the bottom left of this page?
scroll down, waaaay down, look to the left.

you'll see;

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both of those may or may not have exactly what your looking for.

sjkimmel99 said:

I used a wide chain and gears from a 233C (chevy, electrically shifted, maybe from an S-10). I think there are other models that have the wide chain.

Click to expand...

Well Not all 233-chevy's with the electric shift have the wide chain.. I just took one apart that I have been sitting on for a year now.. 1" chain and gears in it, and 3 pinion planetary set up.. it came from a 2004 S10 with the 4.3L v6 and Nv3550 trans..

Arent the 231 D out of durangos etc supposed to be wide chained? Seem like I recall reading that somewhere.

6cyl s-10

Clean-RC said:

Well Not all 233-chevy's with the electric shift have the wide chain.. I just took one apart that I have been sitting on for a year now.. 1" chain and gears in it, and 3 pinion planetary set up.. it came from a 2004 S10 with the 4.3L v6 and Nv3550 trans..

Click to expand...

Maybe this would help narrow down what mine came from. The tag says:

233C
1596 4732 on the assy<something> line
6 30 93 1 on the serial No line
272 on the ratio line.

Could the "93" on the serial number line be the year?

sjkimmel99 said:

Maybe this would help narrow down what mine came from. The tag says:

233C
1596 4732 on the assy<something> line
6 30 93 1 on the serial No line
272 on the ratio line.

Could the "93" on the serial number line be the year?

Click to expand...

Yes your 233 was made June 30 1993

Last month I picked up a 231C from an S-10 Blazer, 94 I think. It had a 4-gear planetary (2 empty slots instead of the customary 3 in our 231J's) and a 1.25" chain, so my TC now has those. Cost was $100 after returning the core. Just FYI for those searching old threads.