20AL with 4 wire line cord

[zaphod01]

I finally decided I had too many 20AL's and started taking pictures of my mystery 4-wire version for ebay. It was the first candlestick I bought and I never figured out the 4th wire.

I removed the mouthpiece and stamped inside was on orange I 36. I assume this means the transmitter was changed out in the first quarter of 1936. Then, I found the transmitter number had been stamped over. This reinforced my 1936 notion.

Lastly, the photo of the perch stamp revealed a very clear '1' stamped in front of the 20AL.

I think I have the mystery solved. I believe I have a 120AL. Photo's attached.