I have a retro kit consisting of the Mag LED switch and reflector. Go to ebay and type in Kel-Lite flashlights, I have it listed at $15 plus shipping. I guarantee you will love it.
Unfortunetly serial numbers on Kel-Lites don't give you any info re: when they were made or any other helpful info. Serial numbers were put on at that time so LE departments that furnished them had a way to ID them.
Don Keller