T case question.....

OK, so a buddy of mine has an 88 dodge dakota and his t case is gone! the truck has 300K miles on it. we came to the conculsion that we are runnin the same t cases in our vechiles. the NP 231, and similair rear ends. i own a 99 cherokee. the only real big differances are his IFS, and lower ring and pinion. the question is, he cant find a matching t case anywhere! (special order truck wen it was new) can he use a jeep T case? he said his was vacuum style engagement. i know jeep did this too at one point, would one match up to his truck? of are there minor differances that i am missing? thanks for your help everybody.  
99 cherokee sport with a costume front bumper. 7 inch optronic lights 30 x 9.5 goodyear wrangler GS/A tires and TJ flares modified to fit my Jeep

He can rebuild his t-case by using parts from another Dodge and a seal kit.  His t-case should have NP 231D on the tag.  You may use the internal parts from a Dodge t-case on your Jeep to beef it up also.  You can also find the parts you need on the net at places like Advance Adapters, etc., etc..  
Just another day in paradise

his case is a special order case. the truck was order to be used for heavy towing and payloads, i think. he cant find it in any other dakota. is it found in a larger dodge vechile? like a fullsize of the same year? sorry, i wasnt looking to rebuild my T case. i was using it for a comparison and to see if he could maybe swap in a t case from a cherokee. like i said, the truck has 300k on it so his current t case will become a back up. he was looking for something with a little less miles on it. thanks for your help.  
99 cherokee sport with a costume front bumper. 7 inch optronic lights 30 x 9.5 goodyear wrangler GS/A tires and TJ flares modified to fit my Jeep