I don't think anyone can give you a answer, since the factory varied the thickness. I found this out when I did my zf swap. I had my truck, 89 f250, regular cab diesel, c6. The donor happened to be a 89 also, regular cab, diesel zf 5 speed. When I did the swap, I noticed the rear driveshaft was twice as heavy as the one out of my c6. Then when I go to put the driveshaft back in place, I decide to use my c6 shaft, since it was a known quantity as far as u-joints being good. That's when I found out the u-joints where larger on the zf shaft. So I thought better of it, swapped the yokes on the rearends, and put the zf shaft in my truck.
Same year trucks, optioned the same except the trannies. Different thickness of shafts and different u-joints.