What if that is the lowest joint and the tail points down........whatcha gonna do then. Would you go positive, if the angles dictated you do that to make it RIGHT in your thoughts, even though positive pinion angle is NEVER desired in a performance car. That's the only question that needs to be answered. What would YOU do in above scenario. Your car, his car, that car..........doesn't matter whos car. If the rule is the rule, what are gonna do if the trans is pointing down and the driveshaft runs uphill. Think about that and then ask "does it hurt" to measure off the tail.

Most big tire cars, with stock floor pans(backhalf cars) that have the motor in the stock location and angle........if the car sits anything resembling low and has a long trans, like a 727......the front joint is almost always lower than the rear. That's why there is always SO MUCH question on this stuff. They slide under there, start looking and measuring. Try to do it like the internet "experts" say and then look at it and say "that can't be right"............And they are correct, it's NOT right.

If you want your car to ride down the road 100,000 miles, be smooth as glass and never have a problem, yes sir, concern yourself with overall driveline angle. Because YES, opposite angles are the smoothest in THAT scenario. But in a RACE CAR, it just flat doesn't matter, PINION ANGLE matters and the two are NOT the same. In a ten second car, you are worrying yourself to death over something that MIGHT be in the condition you deem ideal for about 3 seconds. Other than that, it is all over the place. Just put a go-pro under your car and WATCH the angle and see how long it stays static..........So, you want to measure off the trans, knock yourself out........but it is a TOTAL waste of time. Now I don't CARE what you do. But the fact that you and others think that you have to convince the whole world that it is the ONLY RIGHT way to set one up.........well, that I have a problem with, because in EVERY scenario, it is NOT right.