Wow! A 15 degree angle between trans output and driveshaft is at the ragged edge of any recommendation I've seen. Universal joints are generally designed to operate at 5* or less for maximum life.

Any prediciton on this one is outside my range of experience - or comfort. However, I don't think you have much choice.

More info here:

http://www.iedls.com/IEDL_PTS_LGL_091008_Secure.pdf