There is a little play in the mounting holes for the rear axle or the holes on one side of the car could be opened up a bit in the right directly, any high end mod shop that does alignment could fix this and likely some of the better regular alignment shops if not to far off.
There is a chance the rear axle was not built to spec of course, then it would have to be replaced.
-----------------------
DIY Alignment, basic primer using simplest tools, there are other methods as well but this works very effectively with little cost involved and I still get better results than any regular alignment shop job I have seen.
1)Level the car.
Side to side really needs to be done, front to rear not as important so if not to far off no worries.
If on an unknown surface I use a straight edge as long as the width of the outside to outside of the front tires and a good level then add shims big enough for the side needing raised tire to roll up onto.
Side to side can be corrected with shims under the tires, you must roll the car back and forth to settle out any preload if it has been jacked up, wheels turned, etc. I have some slippery material I place under them, makes it much easier.
2)Center steering.
Rolling back and forth and eyeballing center works pretty well, do not go by the steering wheel unless it sits perfectly straight driving down a level surface, most roads are crowned and can be misleading. After adjusting camber and toe you might have to reset the center but deal with it later.
3)Measure and set toe.
Many ways to do this, for years I taped a measuring tape to the tire first front side of one tire and measured across the car to the other side, pick the same spot on the tread and pay close attention to the reading. Move the tape to the rear side of the tire and measure across again, note the difference. Make sure the tape used as far up towards the chassis as possible and the same height is used on the back as the front of the tires.
This step I do twice as will be shown and if can be skipped but I like to do it here and later as well and if the steering wheel is very far off from center I might center it up at the same time.
Loosen the lock nuts on the tie rods, make sure to not move anything else.
Ensure which rotational direction brings the front or rear of the tire in or out respective of where the rods are mounted, leading or trailing side of the tires.
If a minor adjustment is needed turn the tie rod 2-3 segments, hex sided, 2 segments is 1/3 of a turn, do both sides of the car the same exact amount, snug the tie rod lock nuts, do not need to be tight.
Roll car back and forth and check the results, redo as needed but if very close you can call it good.
(Centering the steering wheel is done by using different turn counts on each side of the car)
3 Alternate) Set toe with Longacre toe plates and two small tape measures, a great time saving and accurate way, highly recommended.
4)Set camber with a level and more accurately include a protractor.
This will get you even side to side which is very important and if you have limited range get you as far as you can go within that range. I have found I had to notch a strut hole just to get them even as seen cars so far off even new they could not be set right.
Ensure tires are inflated to the same pressure, place level on the bottom sidewall and ground, move top in and out and measure gap between level and top of wheel rim, compare to the other side of the car. It is better to use just the rim if possible, I will mic and tape nuts, etc, the same exact thickness, to the level so it only touches the upper and lower part of the rim.
Adjust to both sides read the same.
If you want to know the numbers it can be done with a camber gauge or a protractor, I use a pretty costly digital camber/castor gauge and check castor as well but you cannot adjust castor on most cars without special parts and usually not a big deal, it won't change much from moderate camber changes if any at all.
5) Set toe again as in step 3
6) Check Thrust Angle (front to rear axle alignment)
This one is a bit more involved and I have promised some time with my wife, for now, look up using a string tool, I just use jack stands and some yellow line, fishing line works great as well. I have done full race alignments on very sophisticated race car suspensions and verified it to be very exacting.
I have done dozens if not hundreds of alignments since the early 70's on cars from 510 Datsuns to full out Vette road race cars, trucks, etc....often times wishing I had a 4 post lift and alignment rack for it but only had a two post lift later in life and they will not work for it.
NOTE: I will finish the TA adjustment section probably tomorrow as well as edit the rest for any corrections. Also there are more ways to do these things so post them up if you have them, please