Rear differential ratio

[19531963]

I have a 1963 Dodge D100 that had a factory 6 cylinder and 3 speed manual . I have changed it to a 360 magnum with 727 automatic transmission. When I drive on highway the rpm is really high . What would be a good gear for the rear differential. I think it has a 391 in it now . Thanks

[martincom]

Tire size is also a factor and we would need to know that for a recommendation. I'm thinking 3:23, but would need to know tire size to be sure.

[Jim100]

If you change out the complete third member which is the easiest way to go make sure to check if current one is open or limited slip. You want to save the limited slip. Expensive part.

[Hobcobble]

I have a 1963 Dodge D100 that had a factory 6 cylinder and 3 speed manual . I have changed it to a 360 magnum with 727 automatic transmission. When I drive on highway the rpm is really high . What would be a good gear for the rear differential. I think it has a 391 in it now . Thanks

I put a 2.94 in my '65 D100 with a 318/NP435. It fits the bill for me.
A 3.23 is a good choice as well and probably a bit more readily available.

John

[PwrWgnDrvr]

I have a 1963 Dodge D100 that had a factory 6 cylinder and 3 speed manual . I have changed it to a 360 magnum with 727 automatic transmission. When I drive on highway the rpm is really high . What would be a good gear for the rear differential. I think it has a 391 in it now . Thanks

If you have the tapered axles, dump that POS and get a later rear end with parking brakes.