The compressor in question looks to be an 85 class, get me serial number to make sure.
Henry, the tractor you are dis tubing is a centur, Schramm Pneumatractors ran on 3, compressed on 3. Until you to the bigger units, which could be run 4,compress 4, or some had a 6 cylinder engine powering a 6 cylinder compressor block.
The crawler pictured above is mine.
Give me a call if you need parts or information.
Jim Arras
419-722-0774