As long as it is from an American Standard, yes. An MIM Standard should fit as well.
Yeah, you gotta be careful with some of those aftermarket suppliers. They usually get them from overseas where the specs for the guitars they're intended for aren't even close, or they'll fit Squiers real nice.
Having a Warmoth body, getting a guard from Warmoth is pretty much a guarantee it will fit. Terrapin Guitars does good work too. He cuts them himself.