Not over thinking. You need the third member in with a pinion installed to set your drive shaft angles.
Then I can measure for a driveshaft
I wouldn't do a driveshaft yet. Your angles and length are going to change quite a bit from the bare shell that you have now to when the car is fully loaded down with fenders, tank, interior, etc. For that same reason, 3/8" sounds pretty small for tuning in the rear end after you have the car fully loaded. Just my 2 cents. The threaded ends of my 4-bars are almost 3" long. I have them threaded with about 1" out right now and expect to adjust them further (both in and out, depending on the bar) as I load the chassis with more weight of the completed car.Yes 4 link is built.....pumpkin is not assembled yet.
Current angle on diff is 0, upper rods are bottomed out.
Need to move rear end 4” forward.
Would like to know angle rear is supposed to be, so I can put it there, then measure 4” from that point plus allow about 3/8” on each end for adjustment.
Am I over thinking?
Never been accused of that before!