Thanks for all the info!
I know the Mico lock is not good for a parking brake, that's why I want something on my transmission with spring, or mechanical apply.
The wheel chocks would work, but to be "legal" I have to have a real parking brake in my state. Also, I don't know of any automatic wheel chocks, the only models I am aware of require getting out of the cab.....

I think the Mico mechanicaly applied caliper is the closest thing yet, but not sure if it is strong enough, but could be. I don't want to deal with hydraulic release, although some of those calipers look nice.

Any other ideas out there?
Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-