Hi, Chuck...
This is 54+C(or L?)37. I find best way to read these pre-war codes is backwards, right to left.
So that makes it aircraft 'C' or 'L' of 7.Staffel, within III.Gruppe of the (numerically) fourth unit within air dirstrict 5 (headquarters at Munich). As Revi16 rightly states, that was KG255.
If I understand this system correctly, '255' in itself tells you that: '2' the unit was specifically the second bomber unit within the air district, the first '5' denoted the aircraft type (larger twin-engined, therefore usually bombers) and the second '5' again confirms the air district.
Hope this is helpful
.
Regards,
Paul