If it is assembled and sitting on the ground (so that you could drive it) and with good u joints, just measure the angle between the crankshaft and the driveshaft and mark that down. You can use the bottom of the engine block where the oil pan mounts. That will be a straight line with the crankshaft. Or you can rotate the u joint flange (end of transmission yoke) upright and come off that 90 degrees to get your line. Once you have the angle between the crankshaft and the driveshaft line measured, then do the same at the differential and add ~1 degree at the differential to take into consideration spring wrap-up. Ie, if you get 3 degrees at the transmission and 3 degrees at the differential, make your angle at the differential somewhere between 3.5 and 4 degrees. The wrap-up allowance is something you'll get all manners of opinions about, but over the years I've learned this is something you do not want to ignore on a pickup if you have a stock setup. Fortunately the AD truck was designed with spring under axle. That helps a bit as spring over axle always makes wrap-up worse. And wrap-up occurs both on acceleration and deceleration. The heavier the vehicle is, the worse the wrap-up will be and the more tendency there'll be for wrap-up while driving. If you have 800 pounds of something in your bed then even with really tough springs like the AD has, you'll get spring distortion every time you take off and stop unless you take off and stop very very slowly and just regular driving will cause the spring to flex also. Good luck.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
