We're not looking at extreme angle changes here. I would think when someone raises or lowers their car moving rear axle would cause much more of an angle change. I do think it would be ideal to have a perfectly straight alignment of drive train, but I'm pretty confident that my drive shaft won't fly of going down the road. Having said that I will have to observe any abnormal wear on the U-jolts.
One other factor I've noticed it that raising the Engine. It has caused another minor problem, the kickdowm linkage is hitting the transmission tunnel (this would became even a bigger problem if I raised the transmission side). I'm using a later model linkage (don't know what year) and it has bulky square pivot end. I may be able to correct this by relocating the pivot arm on the transmission, unfortunately this won't as easy to do with the transmission in the car!
