These driveshaft threads always baffle me with the tables and charts. I had my /6 shaft shortened when I put in the 8 3/4. Then I got a new shaft made up when I swapped in the 408/727.
Both times I just shoved the slip yoke full forward, measured center to center on the front and rear yokes/U joints (with weight of the car on the rear suspension) and told the driveline guy exactly how I got my measurement. He would then deduct an inch and the driveshafts were both perfect.
But then again, I wasn't looking for a "stock" solution........
