Numrich is NOT the only game in town, and, .30-40 was one of the most popular chanberings so the "A" parts should be available somehow, whereas your "B" parts might even have some premium value.

S&S? Winchester Collectors Association, etc.

Apparently Bubba installed your "B"s? It sure did not come from Winchester that way.

Or, maybe your rifle was rebarreled?  Might want to check the records at Cody? Since the '06 is known to have given some trouble (not all justified, of course) such a rebarreling could have made great sense to a former owner.

Hang in there!