Hot Rods Pinion Angle

I'm in the process of a frame off restoration of a '40 Ford 1/2 ton short bed pickup truck. It's going to be old school with a slightly built '49 Ford 239 flathead with 2 or 3 carbs (not sure yet), '39 Ford transmission and a '55 Chevy rear.

Can anyone tell me if it's OK to set the pinion angle of the rear with just the engine, trans and rear in place and the vehicle set at the correct ride height or does it need to be completely assembled?

I know how to set the pinion angle as I have done it before a few times but on completed cars.

Any help would be greatly appreciated.

Thanks

Rich

 

The centerline of the pinion shaft must be parallel to the centerline of the output shaft on the transmission. The ideal angle is debated to be 3 degrees, but only because that is the angle that the engine sets at when the carbs are level. The u-joint angles should be equal and opposite, and within the operating limits of the joint, and the driveshaft must be in phase...