I've had a leak in this area for awhile now, and today I broke down to rebuild the booster. In the process of removal of things, I found my leak is only between the master and the booster. Now for the crap part, I can not find the oring, rubber seal or whatever it maybe anywhere. Local, auto zone doesn't have oring this big. Anyone have a part number or a knowing of where I can get the ring?

I'm coming up with a part number of 04723395 for the master cylinder to booster seal.

Edited July 6, 20159 yr by bjytech

Thanks man! I've been looking all over since noon

There is a rebuild kit for the hydrobooster from One Eye Jack's...

http://articles.mopar1973man.com/general-cummins/33-brake-system/79-brake-hydrobooster-rebuild

I have that kit, unfortunately it doesn't have the gasket between the master and booster. Thanks for your input though I really appreciate all the help

Give them a call maybe they can tell you a part number so you can order one or source it out.

On the subject of the hydroboost. I recently did the re seal thatso on the forum. Well the PS pump seemed to be lagging so I went ahead and replaced it. Well I filled the pump and started the truck it felt fine for a second then I started getting a moaning noise the wheel shutters and the brake petal shutters when depressed. Didn't want to start a new thread for this since its related to the hydroboost

You might have air entrained in the power steering fluid. For how long did you have the shuttering for?

It started right after I installed the new pump.I've lifted the front tires and turn the wheels lock to lock numerous times. I thought I solved it but 5 minutes down the road and the brake pedal was pulsating again and the moaning noise was back. But I have noticed that if the engine is over 1100 rpms all the symptoms stop. All the noise is coming from the hydroboost and it visibly moves when it's pulsing.