Here is a source for bus parts, for the coach versus the engine / chassis. (A pdf file.) They're still in business and I had a nice chat with the man, who didn't happen to have what I was looking for, the door seal rubbers, for my Carpenter coach. But he did tell me exactly what to use to make them.
I've had my 1965 Chevrolet C60 Carpenter coach school bus for 30years, as of this month. What a long, strange trip it's been -- four generations of my family have worked on this bus or helped me with it. What follows are recently discovered (by me) solutions to problems and issues I've had for decades.
----------
Here's how to delete the factory Firestone widow maker wheels before they explode and kill you.
"22.5x6.75 White Steel 10x8.75" (Old Chevy 2 Ton Trucks". It's $1800 for all six, but at least you only gotta spend it once-and then tire service shops will let your rig onto their property. With the original RH-5s ... not so much. It's OSHA illegal to even work on 'em. Will make great fire pits, however.
Here's where to get that steering drag link between the Pitman arm and knuckle. Mine was loose for decades, and I bet yours is, too.
Rare Parts with the 5,000lb front axle -- they can sell you #TRDS900 . You'll notice a full eighth of a turn less slop in your steering after replacing this. Also, one less thing that can come apart and kill you.
The front brake drums are a somewhat currently active Webb #64425F and the 14x2.5" shoes are available at O'Reilley's if you can find the right counter person to look 'em up from FMSI #299
Finally, if it's still got the original oval housing 15,000lb two speed rear axle, then it probably has 15x4" brakes and I have a pair of the drums. Fleet Pride somewhat might have the new Gunnite #2770B, maybe. Website says not available for shipping at the moment.
Lastly, to my pleasant surprise, online vendor
Parts Geek has a rather substantial 1964 era C60 parts selection, including wheel cylinders, clutch and brake master cylinders, even some body parts like the inner fender aprons. (1964 and 5 are pretty identical.)
Some of these items I literally spent decades searching for, so now you won't have to. I hope some of this helps you, I sure wish someone had laid all this on me back when I got my bus!
