The frame is made out of 1/4" angle iron (5" x 3-1/2") that was laying around.  It was cut to size and machined out the section for the journals.  The 2 tabs on each cut out will hold the springs in place.

The frame was then welded together...

Cut the frame cover to size...

Cut out the holes for the engine and transmission then drilled and tapped holes and gave it a nice coat of black paint.

Mounting the air compressor (center), the starter solenoid and console bracket was next.  The exhaust pipe was also wrapped in heat resistant header wrap material.