I was trying to change out my leaking master cylinder Cast #5460982 with one I already have but which I thought it was a bendix because it is black and only has 2 Bolts holding the master on. After removing the cylinder, the piston was stuck on the booster and I ruined it trying to get it off. I am thinking I may have a moraine setup since the booster has no bolts holding it together. The new replacement master I have with the same casting #5460982 has the piston inside held with a sir-clip. That's why I thought it must come off. Honestly I am still not sure. Can you please take a look at the attached pictures.

 

Am going through the same repair right now myself. Your booster most certainly is a Delco-Moraine single diaphragm unit.

Color means nothing. If the booster halves are held together with 8 bolts it is a Bendix. If the halves are joined via tabs/slots it is a Moraine.

There are rebuilders out there for the unit. Booster Dewey is one, but he is closed for the month of August.

Brake Materials & Parts is another.

 

So is your piston attached to the booster like mine?
The replacement master I bought has the piston inside it.

 

Here's a Picture of the replacement master.
Worst part is the brakes were working when a took it apart.

 

The replacement MC looks nothing like mine. The repair manual has a schematic of the Moraine MC. The Moraine booster piston does indeed rest on the MC Check Valve/Spring/Primary Cup assembly.

Here is the thread I started on this, which taught me a bit about the booster unit.
Brake Fluid Gone?

 

I know every one i find looks like yours with the 4 Bolt master. Its like I have a cross between a bendix and a moraine.

Do you know how to get the piston off the booster on the moraine?

 

Instead of trying to get the replacement part to work, why not just rebuild the MC that did in fact work at one time?

The folks at Brake Materials & Parts (link provided above) considers the MC and booster to be one unit and will rebuild it for you.

 

I have not been on here since I fixed it. So here's an update.I ended up buying a new piston for my booster since it was like new when I took it apart. Then I used the new master I bought by removing the piston and it worked. I figured they were the same since they had the same casting numbers. Just set up different depending on which booster it went on.