Jock, depends on the style of air compressor. The piston compressors like the old york compressors had a separate lubrication system, and can be converted easily. I believe the old MOPAR compressors could be converted as well.

http://www.offroaders.com/info/tech-corner/project-cj7/project-cj7-onboard-air.htm

the radial units such as the Delco that you have can not be converted.

The problems we face today can not be addressed at the same level of intelligence we were at when we created them - Albert Einstein Or with the same level of $ - Me