Because there is a LOT of (UP/Down) movement in those areas some measured in feet of movement for off road use. if your talking steering column then there is very little movement, more like in millimeters of up and down movement due to body flex and you yanking on the wheel and almost all the a-bodies that I have seen are in a straight line or really close. compare apples to apples not apples to watermelons. A shaft ujoint works fine for a street car even a daily driver. I had a 39 plymouth that was driven daily by me for 10+ years and it never gave me a bit of trouble and it was an U joint that my dad took to the dealership and complained about road wander so that's what they put on it in 1940 and it wasn't welded in either. Dangit I should have kept that car it was awesome. AND the joint was still tight the day I sold it , June 10th 1990. so 50 years of work and still good
can't say as much about the body or brakes but it steered great.
I've turned wrenches 11+ years for a living in my younger days at dealerships, before I found a better way for me to make a living. I'm NOT knocking turning wrenches for a living since I do it now just because I LIKE doing it and it relaxes me too!
