I've looked at different pics of the steering gear and the toothed connection does not have a flat spot that I can see. The bolts sits up above the teeth.

 

I just had my steering box out last week, and mine most definitely has a flat spot on the input shaft so it will only go on one way. And the bolt goes through a groove in the shaft so that it can't pull off, even if the bolt is loose.

 

 

If it makes any difference to you, at one point I used to do alignments in a GM dealership.

Obviously your new control arm has slightly different caster or camber than the old one, throwing off the alignment. The need for a full alignment after replacing the parts you listed is absolutely normal, and I would have alignment checked even if steering wheel was still straight. You can center the steering wheel and adjust toe-in by adjustment of the tie rod ends, but this will do nothing to the caster/camber alignment of your control arm. Alignment will still be off. Take it to a shop and get it aligned - centering the steering wheel is part of it. An Extreme Blazer with with only 58K miles deserves it!

 

I swapped the tires and remeasured, with no apparent change.
What I seem to have overestimated is my ability to figure out if the steering wheel is pointed this way, which way the wheels need to be moved and which way to turn the adjuster to make it so. My last adjustment, after straightening the steering wheel, had the passenger wheel straight and the driver wheel 1/4" toe out. So I tightened the driver end link and well, now everything is lining up. Does not seem possible.

I figure A.) I have screwed up the measuring again or B.) there is factor coming into play that is causing near-random results. My plan is to run down the tires another 1or2 /32" and then get a professional alignment with the new tires (I also have some negative camber on driver side). Before that happens though I want to fix things that are likely to cause a steering issue. Like I said I replaced the UCAs and idler arm, don't know how to check the Pittman or LCA or frame. Sway bar links look good, Shocks are bouncy and when I went to turn the end links there is a lot of play, more than 1/8 turn. Of these items, and any I missed, which ones need to be taken care of before an $100 alignment?

 

Couple of things:

If your steering linkage has any play in it then you will chase your tail trying to set toe in. You need to be able to jack up each side on its own and have no lateral play in each wheel assembly.

Steering wheel straight in the driveway may not be steering wheel straight on the road. I set, test drive and do the final.

As Les said, if you have any caster or camber issues, DIY alignment won't be very accurate

I have set toe in my driveway many times and then put 50,000 miles on the tires with normal wear and good steering feel. I use a tape measure, blue tape and a helper. Let me know if you need some guidance.

George

 

Thanks! Regarding the tie rods, the movement is rotational. Now, because they are linked, the rotation happens in both the inner and outer rods. Does this mean both the ball joints, inner and outer, need replacing? Seems like most replacments are the outer only, but I don't see how one can say it is only the outer end that is loose.

On edit: I changed out all four tie rods and the steering is tighter.