Is this a Merit HVO-6? If not, what is it?

[Kevin Kuehn]

Originally Posted by VintagePC

(Interestingly, the Thor column in the Sams does not list FLY-3 as a replacement option, only the HVO-6. Perhaps the 3 wasn't on the market when the SAMS was published?)

Also interesting is that your sets OEM part number(55C172/B) is listed in my Thordarson catalog as requiring a FLY 12 as replacement.
I tend to believe Thordarson literature over Sams, but it's possible they both will work in the circuit. Often times it comes down to physical differences in the way they mount.