how come

Glad you kid is ok. Funny how things happen and they do for a reason. There is a message in there somewhere. maybe it was time to get rid of the car that got wrecked? In any event you said you needed something that gets good gas mileage you drive the crap out of, why not a 70 Swinger??? If its a slant like mine you CAN drive the crap out if it AND get good mileage on the gas. I do!!!
I agree!!! Before my rearend crapped and I replaced it with the quickest easiest to source rear I could find, I got 25 mpg highway, 15 mpg city and 19 mix. DISCLAIMER: Highway speeds were kept at 55 mph. When I swapped rears, the new one had 3.55 gears vs. the original 2.76. Now I get 22 mpg highway, 17 mpg city and 18 mpg mix.

Why did the highway go down but the city went up? Excellent question. The highway went down in a textbook manner due to higher engine rpms (doing 56.134 mph on the highway confirmed with gps puts the speedo at 70 mph which is 2500 rpm vs 2000 rpm at the original 55 mph with 2.76 gears.) Simple enough. But why did the city go up? Also simple, my slant acts like a warmed over 318 now and accelerates sooooooo much easier. Therefore when taking off from a dead stop (ie. from a stoplight) I don't have to be in the gas pedal as hard to keep up with traffic.

So what am I really saying here? A '70 dart with a buzzin' half dozin' will do you great on gas mileage.

If you live in a rural area and have long flat roads and highways, 2.45-2.76 gears is what I would suggest. 0-60 mph time: 45 minutes. Great cruising characteristics, top speed: faster than you'll ever need to go.

If you live in a semi rural area like me, where the roads are similar to previously noted rural areas but you live close (within 20 miles) to a city that you travel to frequently, 2.76-3.23 gears. 0-60 mph time: 30 minutes. Fair cruising characteristics but highway rpm will be a little high. Top speed: still faster than you'll ever need to go.

If you live in a city where you rarely see anything over 55 mph, 3.55-3.91 gears. 0-60 mph time: 15 minutes (that competes with your avg. Honda). Horrible cruising characteristics over 55 mph and terrible highway mileage and your rpms will be wayyy to high over 55 mph). Top speed: 80-90mph.

Or to make life so simple, install over drive which costs time and money and cutting sheet metal, run 3.73 gears and enjoy everywhere.

THE BOTTOM LINE: These slants can churn excellent mpg's when they aren't overloaded in the city (big cars like later a bodies+numerically low gears=overload) and when the highway can keep the engine around where peak torque is in the power curve ~1700-1900 rpm. By the way, screw power with these engines, they don't have any. They got all the hot sticky bad@$$ torque you'll ever need though. :D