Hey All, My power steering pump failed about a 1000 miles ago and I found no mention on this site of an alternative part. There was however a bunch of info on the Disco sites. So after suitable testing I thought I should add a review of my latest success. I can confirm that the PS pump used on a wide number of GM vehicles, Jeeps, Saabs, and Renaults with 4 cyl engines 1984- 1993 is a direct bolt on to the 4.2L in my 95 LWB. All the mounting holes are in the correct place and correct metric threads. I did have to use the entire original pulley assembly but it fits with the correct spacing. The high pressure line screws right in with no leaks. The only difference is the PS fluid low pressure side (the inlet) doesn't have the 90 degree bend of the original equipment ZF unit, and the pump housing is also cast iron not aluminum. I used a short bit of hose and 1/2 inch copper elbow to redirect the low pressure hose with minimal bends back to the reservoir. I have well over a 1000 miles on the pump - it has performed perfectly, it is quiet, and my steering operates smoothly.
The best deal I could find was through O'Reily Auto Parts the "Cardone #20-874" Napa and others had a similar number but wanted a bit more. I paid about $55 and a $25 core. The saving is not hugh (60-70%) but no one locally (Lincoln, Ne) had the original part in stock (most couldn't get it) and everyone had the GM unit in stock. The O'Reilly website has a extensive compatibility list for this item.
The repaired pump meant I could take the Rover out to my summer job in western Nebraska - I have to include a glamor shot after I gave her a good bath and wax.