so this item is actually what I considered the largest hurdle of the whole project, so I am just glad to have it in hand and done. Everything else is busy work, but getting the drivetrain figured out was going to be the tough part.
I machined the adapter on the lathe at work - engineers don't usually get to use the tools but having a little machining background from my mechanic days bought me some favor
Then I bored the center out to the dimensions Andrew at Mark Williams asked me to hit and took it to him for final splining. They had to rent a special shaper to cut this specific, odd-ball Hemi spline that Mendeola uses but it all worked out bitchin'. Heat treated it to boot - this should be the strongest piece in the whole drivetrain haha.
The batteries died right after I took these so as I feared, the images are a bit blurry (happens every time right before the batts die). Nonetheless, close enough for internet work. The assembly in the aluminum housing is the tail end of a C5 Automatic torque tube - we took it apart so I could machine the driveshaft side a bit and also replace the bearings, which I need to get on order. Basically I will be making a large adapter piece to bolt to the bell on the Mendy that then holds that C5 tail assy and the new adapter piece inline with the input shaft of the trans. This will be a tedious item to make but not difficult.
You will note I have a piece of sheared off input shaft for test fitting - they sent this to me for clutch alignment so it came in handy for making the part v. schlepping that trans over to Mark Williams for fitment.