Power Steering Pump Swap

Hey there, I have a 89 4.0 and was wondering if the power steering pump is year specific. I starts whining as soon as its warm, bad bearing in it maybe? Would you get a junk yard replacement or new in my situation?
Thanks,
Dave

Have you checked your fluid level/color?

Yea, its clean...Its weird, it picks and chooses when its going to do it too...I hate intermittent problems

I replaced 3 PS's in the last year. The bearings for the shaft are sealed and not exposed to the PS fluid. They fail.
I believe they are all the same without the res. tank. If you get one go to NAPA and be sure it has a return nipple that is not glued into the tank. It will fail. Also have them pull the pulley for you. The NAPA dealer I use plulled it off in a few min. Follow the directions for pulley installation. I made sure the pulley was not over installed, that is the belt was properly aligned with the other pulley's.

I just did P/S pumps on both the 90 XJ and the 88 MJ, same part. The only difference was the pulleys.

My MJ has a metal pulley, with no spokes or holes, and mounts flush to the end of the pulley shaft.

My XJ has a plastic (ABS?) pulley, it is spoked, but the spokes don't go all the way through. The pulley mount is recessed, about <1/2" flush with the shoulder inside. I also replaced the pressure line (and o-rings) and the return line.

The return hose on both was a moulded piece, metal lined. I replaced it with bulk rubber P/S hose. My fluid on both was nasty. I've put "flush P/S pump" on my annual maintenance list.