My 78 LRT has been sitting on the side of my garage for the last seven years. I got it running again out of a gas can,and I bought an electric fuel pump to pump the bad gas out of the tank. I moved it and the brake pedal is not fully releasing when I take my foot off the brakes. I figured it may be the brake hoses or stuck calipers,so I replaced the hoses,calipers and brake pads. The brake pedal is still not releasing,do you guys think it's the master cylnder,the brake booster,or both?

Booster being bad will cause the pedal to not come back up. Wouldn't hurt to replace mc and booster

It's likely nothing more than the shaft needing fresh lube.

It's nearly impossible to lube from the ends of the bushing and I had to disassemble mine to clean out the old, dried residue from the bushing. Fresh lube...like new.

Wife 76 wouldn't bring the pedal back up and it was Bad Booster.
Sometimes a bad booster will also produce a hissing sound. My Crewcab currently needs booster. Hisses

Who has the best deals on brake boosters for a 78 LRT?

My 80 had the same problem, I ended up buying a new booster...but that was not the problem. I found that the shaft that the pedal is attached to was rusty and needed lube, I should have checked it first before buying a new booster.

I know that it takes the same booster as any other power disc brake equipped 78 Dodge truck. Where is the best place to locate/purchase one?

I bought my last setup from Rockauto