In the future you can use your angle finder on the end of thetranny output shaft if you want to know that angle
On finding the pinion angle on machined pinion yokes you can turn it so the outside edge of the pinion yoke is aligned with the ground and use that surface to find that angle
I measure the pinion angle their and the driveshaft angle on the bottom side of the driveshaft so I have the zero degrees on the angle finder pointed upwards and go from there, one of the older units I have has 90 degrees straight up and measure the same numbers both ways from straight up
When I would use that one a long time ago I would add or subtract the two angles to get the total differences, IE 88 degrees on the driveshaft and 93 degrees on the pinion shaft angle, subtract 88 from 93 for five degrees difference If I used that angle finder on top it would read 88 one way and 87 the other way so I had to add the differences from 90 degrees to get the total angle, 87 subtracted from 90=3, + 88-90=2, add 2+3=5
Remember that between 3 and 7 degrees difference on a leaf spring car, no Cal Tracs or any other traction bar systems like that, your good. I did set one of my old street automatic cars up with 7 degrees and it would make driveshaft noise(rear u joint to much down angle when deacceleration, when I let off on the other end I ended adding a 2 degree shim on the front side of the springs to reduce the angle to 5 degrees difference and that made that noise go away
Another way is to measure off the U joint caps on the Detroit type U joints from the bottom of each one pointed straight down, you do need the car on jack stands under the rear end housing so the chassis is loaded like it is on the ground so you can rotate the driveshaft to measure off both the pinion cap and driveshaft caps