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I'm not an expert by any means but the 9 degree down angle on a 28" long drive shaft sounds like a problem for the u-joints. I'm sure others that are more experienced in this area will be along shortly to provide insight and correct me as needed.

What WICruiser said. I put your numbers into Spicer's Driveline Angle Calculator LINK and came up with 16 degrees on the rear u-joint. WAY MORE than the 3 degrees recommended. Changing the pinion angle doesn't help much, so it looks like you'll either have to drastically angle the engine down at the back or lower the whole engine/trans assembly to change the driveshaft angle. I was reluctant to respond last night as I figured something was wrong with how I was using the calculator. But WICruiser's response reinforced what I was seeing.

One of us must be wrong in some way. I did the same inputs and it asked me if the drive shaft measurement was a direct measuerement off the shaft or the difference between pinion and shaft, it's the measurement off the shaft. As I see it the difference is only about 2 degrees. I hope I am correct but I have been wrong many times, just hope this is not another of my mistakes.