Don't believe any early 6 cylinder Mustangs used a Holley - just Autolite's as mentioned
Today, I found the following for the Holley 1V carb. According to the reference book Mustang 1964.5 to 1973 Restoration Guide, Copyright 1998 Corcoran/Davis on page199 shows that the Holley Carb was used in 1965/1967 on the 200 six cylinder.
Year CID Type ID Part #
65/67 200 H-1 D0PF-K D0PZ-9510-A
Since the designation 1965/1967 was used, does this mean that 1966 is not included?
There are quite a few listings for the Autolite, Holley and Carter for carbs used on the 200 six.
The reading of this chart shows that the 66 was listed separately and it shows 1966/1967 and 1966/1969.
I would then assume that the Holley I have is for a 1965/1967 200 six.
Jeff