Driveshaft/U Joint Geometry '37 LaSalle Cad 500 Engine-Trans

[carlhungness]

 I have been taking a course in drive-shaft u-join geometry as I am installing a
1976 500' Cad and transmission in my '37 LaSalle. The front motor mounts were done 25 years ago and my memory of doing them is gone. The rear transmission mount has not been fabricated.
       I plan to use the stock rubber mount and chop up the transmission cross-member to make it work. It looks like a straightforward carbide wheel on a grinder job to surgically remove a section of the cross-member to accept the new mount and fabricate from there.
       My problem is as I see it: The stock pinion on the rear end has a flat-face u-joint mount that measures 90 degrees to the ground. It doesn't rise from 6-12 a
matter of 3 degrees which I may need.
       The rear of the transmission is 8 degrees down. Using string I mocked up a center-line, then a drive shaft consisting of two strings from trans to rear end, and
they did appear to be parallel as taught in drive-line geometry.
     The drive shaft angle (I was able to hold one of those nifty large needle- gauge
protractors and just touch the string. I got10 degrees at mid point of the 'drive-shaft'.
    It is my understanding that to figure the operating angle one takes the driveshaft
measurement  10 degrees and subtracts from it the transmission angle, 8 degrees giving us an operating angle of 2 degrees. Three is recommended.
    Going to the rear end we have drive-shaft angle of 10 degrees from which we
deduct 0 because the rear end is not angled. So the operating angle of 10  degrees is too severe for u-joint life, I think.
     It seems to me the rear end has to be rotated  degrees to match the transmission and give us our 3 degree closeness.
     I'd be interested in knowing what the drive-shaft angle of a stock '37 LaSalle is so if someone wants to crawl under their car and put an angle finder on the drive-shaft, half way, I'd appreciate it. I'd also like to know what the angle is at the rear of the standard transmission.
     I'll do some more checking with those more knowledgeable, but for now I am
trying to figure how to cock the rear end 8 degrees up, using milled wedges on the front and rear of the spring locators. But, the  center of the locator hole will now be
pushed back and it will sit a bit higher because of the wedges.
     I wonder if I can have the center hole milled, slotted to allow for the movement and figure out how to maintain integrity in the locator hole.
     In reality the sway bar will not twist 8 degrees, but it appears as though one could just remove the bar from its top mount, heat the mount and twist it 8 degrees and no one would be the wiser. The steel  brake lines will still fit in their original position.
     Suggestions and knowledge is welcomed. I don't really want to put another
rear end in the car unless I have to.