Model A commercial vehicles picture thread!!

[pat in Santa Cruz]

Originally Posted by spdway1

Sorry for the stupid question...What is a Donovan engine and Ryan overdrive?

Ryan made overdrives for Model A's that are a square box mounted to the differential. I do not know the exact dates they were made, but probably around the 70's.

Donovan Engineering makes aluminum A blocks with 5 main bearings, machined to use chevy pistons, lifters, bearings. They call it the Model D 100 hp, with modifications up to 180hp. They are very expensive.

http://www.donovanengineering.com/Bl...delDBlock.html