Not too many aircraft with overhead engine intakes. The Cirrus VisionJet is a modern example, though that's got the whole engine up there (its only one). The F-107A never made it to production, losing out to the F-105.
All B-52s were built in the '50s and early '60s, yet most are still in service and will continue to be until the 2040s! Now that is good design. Imagine flying an aircraft your grandfather flew. Great grandfather maybe.
It wasn't until I was checking the tags that I noticed this wasn't a B-29. It's a KB-50J, the post-war major update to the B-29 design. It has different wings, engines, tail and more. Oh, and I probably should have noticed that in addition to the fuel pods (it's a tanker) are two jet engines. So it's like the B-36, though it served the Air Force for twice as long.
I've concentrated on the bombers and rarities at Pima, but there are dozens upon dozens of aircraft that are fairly common air museum staples. Not to say these aren't worthy to feature, but with limited space here, I figured the standouts were better worth the focus.