Thanks. Further inspection revealed that the fur looked mangy. I wish that the head was intact so that we could have gotten it tested. Go figure; Mark shot it in the head to be humane and put it out of its misery. Now that this is something that I know, I will keep it in mind and let him know.
I am scared now though, and I will definately research rabies more. I do not personally think that the possum had it; it was out in the daytime, and had the mange, but what I did not factor in was that it was stuck inside the old dog run (fenced in by chicken wire and attached to an old garage) and was actually jumping into and off of the wire to try to get over it and out. We could see tracks where it had run and done this before.. it was not frothing or making noises. Just trying to get out of the dog run that it had somehow become entrapped in.
The head is still somewhat intact. Though the bullet did go into the skull. Would this render it impossible to test still? The body is in a plastic garbage bag out behind the garage, frozen as it is cold out. Tied so that no liquid or anything could get out if we had a freak thaw outside. We did not handle it without thick rubber gloves that we threw out afterward.