Stretch-

I didn't completely clean the innards of the vacuum pump. I did remove and clean the main check valve immediately under the vacuum port because it looked like there was dust or some other kind of debris inside the port. Pretty sure I used just soap, water, and compressed air, but very possible I used WD40 afterward as a moisture dispersant or similar. I don't specifically remember using brake cleaner, but I won't swear that I didn't either. I did grease the bearings, roller wheel, and roller coaster part of the timing device before reassembling.

I've since disassembled the vacuum pump, and found lots of oil residue inside the pump. Not sure how normal this is, I can post photos.

I just got done having a good long listen to my frankentruck's OM617 using the stick-as-stethoscope method, with the VP removed.

Definitely sounds like there's something going on in the IP/intermediate shaft/VP area. I'm thinking the VP being reinstalled only intensified a sound that was there all along, and me in my diesel newbness probably missed it when testing it out and listening to it before purchase. This engine is my only experience with any kind of diesel wrenching.

Where's the best place to buy a full VP rebuild kit(bearings and all) and an intermediate shaft bushing?

Thank you, everyone. I've got some more studying to do.