71 cuda 440 six pack
 

I'm putting in a 440 six pack in my 1971 cuda. I have a 23 spline transmission, will this match up? Or do i have to find an 18. I'm finding that the shafts diameters are different because the throw out bearings diameters are different from the 23 to the 18.

That 23 spline is just fine. All you need to do is get a 23 spline disc, and a T/O that fits your front retainer.