I spent hours searching online and calling salesmen to finally figure out what someone, somewhere should have said a LONG time ago.... 68LAC is 2.5 inches ID and 71LAC is 2.75 inches ID. Now when someone is searching for a cv boot, they can find the info they need.

Just measure the cv bell. If its 2.5 inches, you need the 68LAC boot. If its closer to 2.75 inches, you need the 71LAC boot.

I have a 1998 and 2001 king quad that measures 2.538 and a 1990 lt4wd that measures 2.720

Personally, I think either boot would fit either joint. The smaller boot would stretch over the bigger joint and the bigger boot would clamp down on the smaller joint, but they make a big deal out of it when you order boots.