Honestly, Out of the about 20 or so hammonds That I've Played, I've only seen one that didnt have percusion. I suppose it was a CV or Model D.
If your RT does not have percusion, then you must play an RT2, not 3 
I actually have an old hammond manual. If anybody wants, I can upload a few pages
i guess those in the know make sure they get a hammond with percussion
I will say that the majority of churchesI have gone had percussion equipped hammonds
But I have encountered more than a few that didnt
my church was more concerned about the pipe organ effect so in essence when they bought this organ many years ago they were really trying to get a pipe organ it even has chimes on it
when they got a pipe organ they were so happy with it they really only try to hire musicians who can play a pipe organ
I got lucky I played total praise on it and got over because total praise sounds good on anything
they didnt press me because they heard me play that song
if they had asked me to play anything else I dont think I would have worked here