Is an alignment needed?

So I mostly agree with your first paragraph. Yes alot of vehicles with independent rear suspension (I assume thats what you meant when you said IFS )have adjustment for rear camber and toe. Not all of them have both but usually they do. I also agree that you don't need to measure the rear to adjust front toe, it will just compensate for the thrust angle when you do so you don't have to square it off during the road test.

Thrust angle is basically just total toe on the rear of the vehicle so for these trucks of the forum you are correct that it's not adjustable so if it's off you have something causing your rear diff to be mounted crooked. You are also correct in saying that the vehicle will dog track but could still drive straight.

p.s. I don't drink the kool-aid of the shop because i'm a RSE mechanic and have spent a solid consecutive 2 years on the rack doing alignments when I was an apprentice

 

Depends on how your truck sits mine looked like the camber was off lol … it will prolong the tires if you get alignment it’s pretty cheap .