[Woodchuck]

Are the bolts for the rear end center section on the front or back of the rear end? If on the back you have the 7 3/4" , 6 cyl rear end.

That would be 7-1/4. The 7-3/4" ring gear is in an 8-inch rear.

 

[Woodchuck]

What does that mean... Will it work?

Sure it'll work.... What @gt350sr is trying to say is that gear ratio choice determines how the car will respond to engine power and speed. A higher (numerically lower) ratio will provide a lower engine speed (rpm) at a corresponding vehicle speed (mph) than a lower (numerically higher) ratio and better fuel economy, but at the expense of acceleration. Conversely, a lower (higher numerically) ratio will provide better acceleration but at the expense of fuel economy and engine rpm on the highway. Literally a TON of Ford products left the assembly lines with rear gears in the 2.80:1 range.... some late seventies models as low as 2.47:1 once the government mandated fuel mileage standards.

 

[Woodchuck]

2.83 is a 7-1/4” ratio.

A valid point.

 

[Woodchuck]

That's an 8 inch.