9 3/4 rear end

[GeneralLee440]

So when I got my Charger in July I did some research and found that my car now has a 9 3/4 rear end. I havent took the cover off yet to find out what gear ratio it has but my question is, is this a good rear end for my .30 over 440?

[RallyeMike]

9-3/4 Dana is the cream of the crop, if that is indeed what you have. You can figure your gear ration by jacking up the car, spinning the tire by hand and counting driveshaft rotations. No need to remove the cover 

[six-tee-nine]

9-3/4 is indeed AKA the Dana 60.

They only came in factory 440 powered 4-speed cars. If you car was born else than that it was added later on.

Stock mopar ratio's for the Dana were 3.55 being the trak-pak option or 4.10 being the super trak-pak option

[GeneralLee440]

Thanks for the replies guys. Well my Charger was born with a 318 and an 8 3/4 but when I got the car someone put a 440 in it and a 9 3/4 rear end.
When I jack up the car I count the revolutions of the driveshaft to one revolution to the tire?

[GeneralLee440]

9-3/4 Dana is the cream of the crop, if that is indeed what you have. You can figure your gear ration by jacking up the car, spinning the tire by hand and counting driveshaft rotations. No need to remove the cover  

Well I did some research and found MyMopar diagram of different axle covers and the pic matches a 9 3/4 which has 10 bolts in the cover

[six-tee-nine]

The easiest way is to look for a ratio tag. if its still there its between one of the cover bolts.

If its an original axle it will most likely be 3.55 or 4.10. Can be higher also if the car had a race history.

jack the car up if you need to know the ratio. Car danas had a factory clutch pack limited slip differential so jack up both sides of the car for easy operation.
Mark the tire and the drive shaft and rotate the wheel 1 turn and keep count how many times your drive shaft turns. f.e. if it does 4 and just a little you probably have a 4.10/1 rear end ratio if its 3 and a half turns you'll have 3.55 gears.

[GeneralLee440]

Well i cleaned the rear cover and found out its a 9 1/4" with 3.55 posi. Now my next question is can I put 4.10 center in it?