Trans and rearend choice

[six-tee-nine]

Need some advice on deciding what tranny to get for my '69.

Since i have no gearbox at all for now all options are open, but what would be the best choise?

First is what i'm planning to built as it comes to an engine : i'm lanning of building a 440 stroked up to around 500 cubes, with a goal of around 500 HP. The car will be for street use only and maybe a run at the dragstrip once a year just for fun...
I'll put her onto some pretty wide tires, something like 275 or 285 in the back onto 17" or maybe even 18" rims a decent bit of grip will be there.

Now the gearbox question : will an 23 spline 4 speed hold or am i better of with an 18 spline? Another option in considering is the Keisler TKO 500 conversion kit because all the hardware like bellhousing, cables an wiring comes with it and i need it anyways.
Considering a good quality rebuilt of an original 4 speed an gathering al the parts what is it going to cost me in that case?


Last but not least : my Charger came with an 8 3/4 rear axle, strong enough? or should i trade her for a Dana?


Thanks already.

[Chryco Psycho]

at 500 hp the 23 spline will be fine , otpions are the 18 spline or the 18 spline OD from Passon , Keisler is an option also , I am not a big fan & I wonder how much HP & abuse they will really take , the factory 833 is generally as strong or better
y
I have broken a # of 8 3/4 diffs but I had good traction to do it , if the tires will spin the diff won`t break , if you are planning to use slicks & or other traction devices you will need the Dana sooner or later