I saw that this company rebuilds Knee Action Shocks, if that's what you're looking for. They're in Weymouth, MA. No first hand experience with them though.
I didn't know Bill real well but I did a tshirt design for him for a family function when he was battling ALS, and we talked some. My uncle also had ALS. ALS is a tough one.
Bill was the best in the business for a long time. Didn't change under Andy.