Hey Tim - the obvious interchange model would be a Model 70, which is he same vintage and should be exactly the same frame as a Model 100. As far as I know the Model 71 frame should also be exactly the same (except possibly having some additional holes in the sides). I believe the Models 72 and 73 would also be the same except they would have the Quick Attach latch welded on the front (and possibly some differing holes on the sides).