Spotlight Altimeter Calibrator

Hello
I was wondering if there existed anywhere a diagram of the spotlight assembly, ie the two Aldis lamps on the Type 464 (Provisioning) Lancasters of 617 Squadron, that were fitted for “Operation Chastise”. I’ve seen diagrams showing the positioning and direction of the lamps on the aircraft etc, but have yet to see a close up picture of the way the Aldis lamps were retro fitted into the forward camera aperture and rear fuselage. I presume they would have had to cut a hole in the rear fuselage and design securing brackets? Maybe diagrams don’t exist showing them in closeup, but I thought I’d ask the experts out there.

Many thanks in advance..