The only contender brl that will not fit a "conender" is the 209x45. The 209x45 is for the G2 frame only.
The rest of the contender brls fit the contender or the G2.
There are those who maintain real early frames have trouble with G2 barrels and newer frames have trouble with early barrels. I have a real early frame that works well with all my barrels, and some real old barrels that work well with my G2 frames. I did have to do some fitting of locking bolts, but they seem to work fine all around.
Also, one of the custom barrel makers makes a couple of barrels that only work on G2 frames. I don't recall which one right now. It is on their web page.