Brake Question

[campingman]

Spring Retainer that goes in between the Hydroboost and the Master Cylinder broke. Can't fine it anywhere. I put the spring and push rod back in it without the spring retainer and the brakes work perfect. You think it will be ok or should I hunt down a spring retainer for it? Having a hard time finding one. Brakes work perfect after installing the new master cylinder but when I took off the old one, the spring retainer flew out and was broke. the teeth that hold it in was rusted broke. Its a 1975 GMC G3500 Camper

Photo is what im talking about. The washer looking thing with the rubber in the center the pushrood goes through.