what kind of? and what is so special about the gear oil for the NV3550? is it synthetic? i seen in your jp artical about the tranny swap into the comanche. what kind of oil did you guys use i thought i seen royal purple off to the corner.  

It is a synthetic oil and I have used royal purple synchromax ( which I got at the local parts store)in mine for about 3 years now with no problems and I currently have @ 75k miles on the wrangler.

I have seen that at a quick change locally they don't have the royal purple so they use pennzoil syncrmesh.

Hope this helps  

thank you i figured since like the haynes said mopar gear oil it would be synthetic. wonder since i toped it off last time before with 8090 if that made it die a bit