Driveshaft Angle

Whats the highest operating angle a stock rear driveshaft could be?

I have heard it said that 15* off from the t-case outpu and diff pinion is about as far as a normal u-joint will work. I think that comes from Tom Woods' site

depends on usage. the first thing that will bind is the XJ slipyoke. grinding it or using a YJ slipyoke will give you a lot more angle. 15* sounds about right for something that is going to see street time. if it's trail only you can pretty much go as high as you want until it binds.

the more the angle, the faster the joint will wear, not to mention t-case output bearings. bindage=breakage.

So what gives the XJ drivetrain vibes is an extended slipyoke, right? I've got a D44 in the back of my XJ with the stock D35 driveshaft, along with a lift. My slipyoke looks better than stock, with about 3/8" of inward travel (not a problem when flexing). Should it be a problem if I say, put on a 1.25" shackle then?

alright.. well since im doing the front d-shaft/DIY SYE.. i have the pinion pointed towards the output shaft at the t-case.. if the angle of the shaft is 17* in comparison to the t-case, would that be alright? too much angle for a front d-shaft?