3" or 2.52" is the pitch of the track & therefore the drivers, it's just the distance between cogs.
Crap, Bearcat you're right... no more 144.
btw, for a 146, you'd want this one, the polaris version, not the doo version.
9145 Challenger Extreme 15 146 2.5 53 full 2.86 Center Port for Polaris
Which is a 2.86 pitch, and I THOUGHT (someone correct me if not) that you could run the 2.86 on our drivers... or was it just the other way around? Either way, I'm sure you can get drivers from Avid.
here you go
https://www.avid-products.com/store/ProdDet.cfm?ProdID=121
IF I could get a 141 2.5 or 2.6 I'd have one... wish they made it. Honestly, it's tempting to get that track, as the new CE is a great track! (even if you have to add 5" of track to get there.)
On the M we're able to put a 156 on a 153 skid... not sure how much track a big wheel really takes up, but you MIGHT be able to get away with it, not sure though.