Hi everyone,Im new on here.At the present,I am a 69 year old speed nut that is installing a 440 mopar into my 1981 f-100 stepside pickup.Yes, there is plenty of room to do this transission.My question is, what gear ratio should I use in the 9 inch rearend that is there.It is a 273 gear ratio at the present.I do want to get some milage out of it,its not going to be driven daily.Thanks for the help.

 

It depends on what you're going to do with the truck and how tall of a tire you plan on using....

 

Well with a 2.73 gear you can probably do 120mph in 2th gear with an auto trans. Some thing around 3.23 would be a better choice

 

3.20-3.50 range would be perfect.

 

Welcome!

Tire size, transmission and vehicle use will play a factor as to exactly what gear ratio to go with but I'm wil everyone else in saying 3.23 to 3.55

 

Welcome to the forum.. Be sure to check out the Mopar of the Month contest....

 

welcome to the forum

 

We need photos!! LOL. Yup. Depends on whether you want a short range "fun" rig, or a long range cruiser, and you need to start with the tires you are going to run.

Nowadays, highway rigs run MUCH lower RPM, but my old 70 440-6 RR ran almost exactly 3K at 70 MPH, and it got 14 mpg (with a Holley 800) and headers.

Nowadays, alcoholized gas will drop that some.

The diameter of the rear tire you want to run and what you want for an engine RPM at cruise speed is where you start. If you have the engine "cammed up" don't go too low on RPM