One Used Mopar Part #784-891, Left Front Door (Drivers Door) Window Regulator, is for:

1937 1938 1939 Plymouth 5 Passenger 4 Door Sedan.

1937 and 1938 Dodge, DeSoto and Chrysler 4 Door 5 Passenger Sedans (except Chrysler Models C15 and C20)

This regulator operates as it should. The gears are good.

It needs a spring underneath one roller that operates the lower glass channel (see last photo)