Would it happen to be:
http://www.cumminstools.com/browse.cfm/4,1485.htm

This appears to be the only mill/drill they sell.
The information indicates it is an R8 spindle. There's
a lot of R8 tools and collets available via eBay.
Before doing the welding gig I think I would at least
try an R8 collet. For what it's worth! sdh.

John Husvar wrote:
Well, the boss finally broke down and bought a mill -- sorta.

It's from Cummins Tools, those guys who periodically descend on some
unsuspecting town and hold a "Truckload Tool Sale."