When I am asked about the used machine I would buy, my top choice is the Lincoln Classic II with the Deutz engine. It was the simplest most reliable diesel welder ever manufactured. The welder part is basically the same as most Lincoln welders with AC auxillary. 
 
The Deutz F3L1011 is a very common industrial engine with a long history of reliable service.
 
The Weldmart Idler upgrade system replaces the orginal solenoid in the original Lincoln system. Lincoln has obsoleted most of the repair parts for this machine.  Our system incorporates an "isolation relay" that protects the fragile Lincoln board from solenoid initial overload. This upgrade does not replace your original pc board. Must be used with Lincoln board.