300k or so on 1988 240DL N/A with AW-70 transmission.

I just got finished replacing the in-tank fuel pump (thanks in large part to Brickboard and Art in particular who private messaged me several times with help). Predictably The fuel sock was torn and the hose connecting the pump to the sender line was torn. The bigger problem was waiting a week for the right brand of fuel pump, which was a major inconvenience.

I'd like to do some preventive maintenance so that I don't have this much down time in the future.

I believe that the main fuel pump will be next to go. What brand(s) are good?

What other preventive maintenance should I do at 300k miles?

About 15 years ago, my 1980 DL had 300k when I believe that the driveshaft wore out. The car clunked at the top of first gear for sure and I think that the driveshaft was loose (can't recall which end) and I remember getting something big, but not the differential, from the junkyard to replace it, so I doubt it was the u-joint.