So have to go and get my driveshaft made/ordered.
Before i do that need to ensure that the axle is in correct position (centered) and the drive angle is good for measurement.
So guess best way would be like this ?
Get truck as level on ground as possible.
Engine at around 3 degrees up
Place differential around 3 degrees up
Use string or measure from front tire to back tire on both sides to ensure equal from front.
Same again for axle on center pins - equal distance from pins. Clamp down.
Then measure distance from output shaft to 8.8 flange as per driveshaft builder requirements.
About it.
Then when i get the driveshaft - adjust the rear up.down as required to best get right driveline operating angles here
https://spicerparts.com/calc/driveline/index.html
Obviously hoping not have to adjust much at all else then might have DS length issue.