Delco Booster Question - Missing Part?

[Mike Travers]

So, I bit the bullet and decided to rebuild the Delco Moraine brake booster in my '63 Deville due to a super hard pedal. Thanks to the many forum discussions on this site, I got it apart with no issues (and I'll post the removal tool I built later in another post and lend it to anyone who needs it).  Unfortunately, I realized that I am missing the "support plate seal retainer" (see picture) that looks like it goes between the booster and the master cylinder. I believe the booster is original and has never been apart as the car only has 57k miles on it so that means I'm probably the culprit for the lost piece. When I got the car, the master cylinder was dry and rusted inside. I replaced it with a newer style master cylinder and, unfortunately, threw out the original master cylinder (and I usually keep EVERYTHING). I'm guessing the support plate seal retainer was probably on the original master cylinder and I probably trashed it along with the master cylinder. Is that possible to do or would that retainer plate been pretty obvious and split apart from the old master cylinder? Also, I'm guessing that plate/seal is required to hold the vacuum in the booster? Also, without that plate, could that have been why I had no power brakes because of no vacuum in the booster? All that said, does anyone have a support plate seal retainer for a Delco Moraine that they'd be willing to sell?

[Mike Travers]

Thanks for the reply but these are definitely too hard and not normal - I almost have stand on the pedal. After more research, I think I'm definitely missing that support plate seal retainer. I'm hoping someone can come to my rescue and either sell me just that support plate from an old, damaged booster or even sell me a whole booster that I could rob that part from.