My 72 Galaxie equiped with a 351W 2 barrel is completely factory original. It gets between 12 and 13 mpg.
My 2-door 72 Galaxie was picked up by me in Detroit in July 1972. For over 21 years it never gave me an instance of trouble, but it was routinely maintained. When rear-ended in 1994 by an unlicensed driver in a Cadillac at 35 mph or barely slowing down from that speed, I found a replacement Galaxie 500. Each had the 400 engine. The original had cruise control, but I have not as yet transferred this to the replacement car.
I always use 91 octane, rarely 93. With A/C on the fuel consumption is about 16 mpg on cross-country straight/level roads. With no A/C I have done 22 mpg on a tank. A year ago I took a 6,000 mile 2-week trip and the whole trip averaged 16.5 mpg which included large city traffic driving.
I have added a Pertronix ignition, which has helped increase fuel efficiency by 10%. I've also added XM radio which is a delight. Ford got this car designed right in my judgment.
These cars were designed for best fuel efficency at highway cruising speeds. That was 70 mph back in the day. Before I replaced the distributor I only got about 20-21 highway, since about 23-24 mpg. Around town it's about 12 mpg. I've also had two 1972 Ford Customs (lowest level Galaxie trim) that had 429 Police Interceptors in them, they were ex-State Police cruisers. Pretty impressive performance considering they had lower compression than previous years, they were designed to run on regular gas. My first car was a 1969 Ford Custom with a 428 Police Interceptor; that was a REAL performer! I'm told that was basically the same engine Ford put in the Shelby Mustangs. I'd love to find one of those again. Who cares if it had four doors and was a crappy powder blue!
Please tell me how many bolts does the tranny have for a 72 Galaxie 500 hard top 400 big block engine.