Humm,
lots of parts on line and most have good service and fast shipping. But I agree with gwdixon about Messick's as I have ordered and purchased parts from them. They have tects on had to evaluate and answer your questions, good dealer.Zimmer Tractor in Monroe was another on line dealer who I purchased a Skid Shoe Assembly for my RB3584 Back Blade, another good dealer that I would recommend, good luck with your choice.
DevilDog