It's impossible to overstate how long these things have been in service. The oldest B-52 airframes still in active service were built longer ago than the first flight of the Wright brothers was when they were built.

And likely to be in service for another 30 years. A 100 year airframe

I worked at Boeing Wichita (which is no more), and an engineer told me that the B-52 was getting heavier over time because the old wires weren't removed for avionics upgrades. Of course, they were always trying to put one over on me as a newbie (I worked on avionics S/W in Ada for the tankers).

He also said a big problem was the expense of doing a modern engine upgrade. Anyone know if they ever re-engined it? Was he joking again?

Having one of these fly over my apartment on Rock Rd. was a dish rattler--I used to see B-2s every once in a while too (fairly loud too, IIRC).

20 years later, looks like they are taking RFPs for re-engining:

[PDF] https://crsreports.congress.gov/product/pdf/IN/IN11413

I guess he was right about the engines.