I've putzed with tracked vehicle concepts, but the real things are so high maintenance
in comparison to wheeled-vehicles, plus they're slow and aren't suited to long distance
travel, that I've pretty much shelved them, except for maybe remnants of military/govt.
forces who have access to spares, or an organized group who took over such facilities
and have people who can do the work.
Wheeled vehicles make more sense for the average survivor scenario.
Thou preacheth to the choir, as my shoulder muscles involuntarily ache every time I see someone talking about purchasing a tank 'for fun' but in Buzzbomb's case, in a world where logistics have been severely attrited 'light' armor (like BMPs) would likely become the sustainable MBT. File this under the One Eyed Man being king in the world of the blind.
I've mentioned the Israeli nuclear powered laser gatling armed Centurions from the TEXAS ISRAELI WAR OF 1999 in other threads.
Within that novel (written in 1974) the Texas Armored forces included a substantial number of reconstituted antique gate guards (Stuarts and Shermans and the like). So imagine an M5 with a non-standard (but maintainable) diesel or gasoline rat-rodded into the engine compartment* and a .50 M2 Browning replacing the demilitarized 37mm main gun (for which ammunition is rare anyway).
* Fun fact - the Yugoslavians kept their M36 Tank Destroyers running with T55 engine packs, long after the Ford GAAs gave up the ghost.