[Amps] Ameritron QSK-5PC Query

[Val Erwin]

Howdy.......
 
I recently acquired an Ameritron AL-1500 amp with the internal QSK-5PC QSK board.
 
On the internal QSK-5PC board are mounted two identical protection bulbs designated "LP-1" and "LP-2".   Does anyone happen to know what the commercial part number of this bulb might be, other than the Ameritron designation of: 420-0164?
 
My bulbs are "OK" now but I believe in being prepared if/when they should fail!
 
TNX
 
Val Erwin
W5PUT
QCWA Natl' Director