Did Paraguay not buy up a load of Sherman upgrade kits from the Israelis too? Could just buy a Company B Super Sherman model and that I guess.
Nope, You are probably thinking of Chile. They bought Israeli Shermans in the late 1970s and 60mm Hyper velocity gun kits for their Shermans in the 1980s. All long retired. The Paraguyan Shermans were, IIRC, all ex-Argentine Fireflies,some of the ones they didn't convert in the 1970s/80s as part of their
repentenciado program (basically a French 105mm and a new engine).
Whilst there are numerous examples of T-34s and other WW2 era museum pieces floating around into the early parts of this century and even the odd one to this very day, you need to be careful about a lot of those lists, including Wiki the IISS etc that show such items in inventory. Most are purely nominal as spares dried up yeas ago. Some never even existed like putative T-34s in Guinea-Bissau. If you are having difficulty getting the 1950s/1960s era T-55s in your inventory running how much more likely is that you have operational 1940s era tanks?
In reality working WW2 era vehicles are much rarer than wargamers seem to think.
The Brazilian X-1A s (Stuart derivatives) are all in museums. All long out of service. Uruguay had some M-24s until a few years ago. Replaced by ex Brazilian M-41s and other kit. Colombia still had quite a few M-8 Greyhounds running around until relatively recently, including a local TOW armed AT version but I think they've all gone now. From memory I think Bolivia was one of the last users of Stuarts, again all out of inventory.