I have a mostly compete W140 S class M104 that suffered a HG failure/warped block and I will be tearing down it with my local university "for science" and to get a end table out of it. This engine ran poorly in the W140 before I pulled it to drop another engine in. It appears to be a victim of overheating as the belt was shredded and wrapped around the water pump. I would not sell this pump in good faith.
I also have some W124 M104 parts (MAF, intake crossover, second set of coils, and exhaust manifolds) to sell.
PM me if you're interested in any of it or want more info.