1985 chevs s600 red button on dash

[85s6000]

Me and my gf just bought our first bus and i drove it home and there is a red button on the dash that I have no idea what it does. It's a 1985 chevy c60 bus with a 366 and an auto. It looks like it has air lines running to the button and from the button it looks like it goes to the back of the transmission. Any help would be greatly appreciated!

[opus]

2 spd rear axle probably.

[85s6000]

Not that I can tell, that was my original thought but the red air line runs to the rear of the transmission as far as I can tell. I'm gonna do sone more looking tomorrow though.

[opus]

PTO? OD? Ejection seat?

[85s6000]

Maybe overdrive but if it is that it doesn't work I pushed it in and pulled it out nothing seemed to change. Maybe ejection seat though!

[opus]

We need a picture of it.

[85s6000]

I'll definitely get some tomorrow!

[opus]

TOMORROW??? However will we sleep tonight with that suspense hanging over our heads? ;)

[85s6000]

Couldn't let you stay up all night. Bad picture but that is the button. I'll take more when I get a chance.

[opus]

Well, I'm stumped. Manual door open, air door close. LOL.

[Booyah45828]

Parking brake on the rear of the tranny of some sort? show us where the lines go.