Can a DSWM3 be used on a AT9 dish ? or only a Slimeline ?

My old AT9 dish is still working great. its mounted on the side of the house above the backside
of the garage, easy access. But its feeding a Swim16 with 4 cables, can I put a DSWM3 inplace
of the AT9's LNB and sidecar and only use it for 99-101-103 with the DSWM3 and will it fit in the
slot opening or will all the geometry be messed up and cause strange alignment issues ?
Also will the larger size help or hinder signal levels if it will fit ?

 

I think the J-mount pipe diameter is the same, and I recently checked it for level, so might just get a Slimline and use the same mount, mine is mounted to the side of the house and not the roof, so No holes that might leak. the DSWM3 would work fine, since 3 HD dvrs, and a HR44 Genie, so 11 tuners or does the genie use 7 tuners or just 5 ?