Patriot door rollers

I have a Patriot sliding glass patio door that needs new roller assemblies. The door was installed in the 1998 time frame when the home was built by Ryan homes. I would prefer to have the replacement assemblies in hand when I remove the door so it doesn't have to be removed and reinstalled twice. Can you make any guess on which roller assembly might be the right one. If I order it and it is not the correct one do you allow return and exchange? thanks, Chris