Mark told me that the conduit enters at the lower right quadrant of the Gyralite (as one faces the back of the unit). This, together with using the PAR-56 7" bulb, indicates that this is the 17570 Gyralite.
This is a single beam Pyle Gyralite. It came off of a Frisco locomotive,
later Burlington Northern as indicated by the BN green. This one appears
to have come off an EMD unit as all the Frisco GE units used the flanged
style casing.
Bill Kaufman