I've got two PE sets for the M24, the first from Ordnance Models (kit n. A-032) and the second from On The Mark Models (kit n. TMP-3515). I've got no clue if they're still available, but both of them are very basic an are mainly made of fenders supports replacements, that are quite easy to be scratchbuilt using copper/brass/aluminium/soda can/etc. foil. I got them for free I don't even remember where or when, but I don't think both of them deserve their cost. If I had to choose what to to buy to enhance the kit, I'll go for a new gun barrel and/or a new .50.

(the upper one id the Ordnance PE set the lower one is from On the mark)
Ciao