1969 gmc 427 6500

[Old Truck Man]

Ive owned lots of those type of trucks over the decades. The problem lies in the fact that they are not driven daily. and the hyd brakes dry out. and they are expensive to work on. The brake booster cost around $400.00. and they are hard to find. The last one I replaced I had to send my old unit off to get it rebuilt. My current C65 has full air brakes. If you got enough air pressure to release the brake chambers you will have brakes no matter how long its been setting. Ive also owned a couple of those air over Hyd rigs and they weren't so great also.