'85 NP 229 No Low!

My '85s NP 229 won't go into Low Range. It grinds, and will not engage. I don't want to bother fixing it - I'd rather replace it with a 231. My tranny is a 3 speed auto behind my 2.5. What YEAR donor 231 do I need?? How about one from a Wrangler? Will it bolt up? My tranny is the 999.

If you shut it off, can you engage low range? It sounds like your vacuum front axle is causing a problem that a new tcase won't fix. Since it's 904 automatic, it'll be 23 spline. If you go weak NP231, it has to be 4.0L '91 or newer and will need a 7/8" spacer/clocking ring (that's what I bought) I would snag a Jeep NP208J (full size rigs had them) and get a 23 spline bolt in (rear driveshaft will need to be longer) that doesn't need a $$ SYE kit.

It won't go into Low when shut off. 85's don't have the vacuum front Dana 30 disco. They have a Selec Trac sytem w/ a vacuum 2wd/4wd engagement straight to the TC (NP229). Yes, my mistake, my tranny is the 904 NOT the 999.

Hey Barillms. How ya been? Is your grinding sound a slow grind or does it sound like the transfer case is spinning at full speed? Check your linkage on the tranfer case to see if it bent or moved. If it is grinding alot than I would think that the t/c is out of 4wd.
Before I took out my original 229 I would be in 4wd and try to get to 4lo and it would pop right out of gear and start to grind. I adjusted the linkage to find out the previous owner had never taken care of the linkage problem and would just let it sit there and grind away. So that t/c was a loss. Let me know how it goes.

Kim.