rear end

[coronet318]

Hi again, another question from a newbie.
I own a 69 coronet440 with the 318 motor, 727 trans and I have now clue what rear end I have. I was wondering if there is any way to find out. I have the original receipt for the car bought in 70' and it says I have 2.42 gears but not the axle size. My 2nd question is, if I have the 8 3/4 can I just swap the 2.42's out and put in 3.23/3.55 with a posi into the same case, or would I have to buy an all new case(I don't know what its actually called but it is where the driveline hooks on to). Also does anyone have any recommendations for companies that sell the complete or will reassemble mine?
Thanx again

[rumblefish360]

Stand behind the rear bumper, look under at the rear. How many bolts hold the cover on.....times up...if the ans. is non, then you have the 8 3/4 rear. Randys ring & pinoin sells complete set ups. There a bit of $$$$$$ though.
If it is the 8 3/4, and you re-use the old center section, you can get a suregrip from MoPar or an Alburn unit. Then go & get the gear ratio you want. Just slip it in. BAMMM your done.