I took a closer look at my seatbelt configuration. I'm thinking that the "plastic sleeve" is very likely a standardized piece made or distributed by many. Just to confirm, we are talking about the piece on the inside of either front seat that recieves the belt when you buckle up?
I noticed that mine had a crimp in the plastic just above the round button where the sleeve is bolted to a cross-rod under the seat. I can see where repeated outward flexing might cause the plastice to crack or tear.
What I don't know is this merely a sleeve with the webbing/attaching plate/receiver buckle inside or is it an entire assembly?
I still believe that the AMSafe source was most likely Gulf Stream's supplier. That said, I also believe the
www.wescoperformance.com link will get you a correct replacement as well.