What puzzles me is they say you have to supply a core, but not what kind of core. Lots of typos in that ad, but not all gearheads can spell.....

Is the 0.69:1 overdrive ratio the stock 518 ratio?

When I first got my '64Dog on the road it had 3.91 gears. With 32" tires it got about 14mpg at freeway speeds. The motor was the stock Poly 318. Then I swapped rears for a later (one piece axles) with 3.23s. Mileage didn't change a bit. It made a lot less noise running at 80, so I kept the 3.23s. But there was no mileage gain at all.

R.