Bacchus203 - I have read your contributions to the "Best $200 Mod" many times as I go through this project... THANK YOU! You were extremely helpful and concise in your explanations (and continue to be). Yes, I plan on doing exactly that... cutting under the dash, filing the Mustang shaft to a DD, then I will modify the U-Joint to retain the splined section and weld the DD coupler to the other end.
Is there any trick to filing the shaft to a DD? Just a file and check the fitment of the DD every now and again?