I received the new shorter driveshaft from FFR today. This one is 3/4″ shorter than the old one, so it should fit fine.
I had to loosen the engine mount bolds and remove the lower transmission mounting bolts in order to shift the transmission to the left enough to slide the slip yoke over the transmission output shaft. I then slid the aft flange in place and installed the bolts. Given the mechanical advantage of the diff, I couldn’t hold the rear wheel in place firmly enough to torque these bolts, so I put the transmission in gear to prevent the driveshaft from rotating.
The driveshaft is just short enough that the seal rubs on the slip joint instead of the face of the u-joint.