A .308 or 30-06 will have the standard size threads and the magnums have slightly larger shanks.
Correct that the 308 and -06 will "typically" have a standard shank size, but the normal magnums will also be standard (300WM, 7mm RM, etc).
The WSM's, most RUM's and the target action barrel's (some 223, 308, and others) have a large shank size.
I got an aftermarket douglas 30-06 heavy barrel with a standard shank, and have had, at different times, factory varmint barrels in 243, 308 and 300 WM.
I probably didn't have to get the aftermarket -06, but it was a good deal. All the factory barrels I had shot dandy.
the website posted by skunk will take care of your barrel itch.