Nagging Steering Issue

[gringoloco]

A while back, I replaced my steering box on my '70 C10, due to leakage issues, with a rebuilt unit from an '84 C10. I figured if I was gonna spend the money, I might as well reap the benefits of the variable ratio and fewer turns lock-to-lock. This was a direct, one-for-one swap, with no other changes made. Bolted right in like it belonged there, with the exception of the high-pressure line (different fitting), which was in need of replacement anyway.

Since that time, I have had the issue of the steering box being off-center by 1/4 turn, meaning I can turn MUCH sharper to the left than to the right, my turn signal lever will not properly cancel, and is causing undue wear to the steering box internals due to being off-center while driving. Not to mention the less than desirable 'twitchy-ness' driving on the highway. I have had an alignment performed (maybe two) that did not correct the problem, though I did not specifically ask them to. In my attempt at fixing it by turning both side's tie-rods equal amounts, the 'short' side bottomed-out before the wheels were centered. My concern there is that even if the tie-rods were adjusted enough to compensate, I would have one side dramatically shorter/longer than the other, leading to bumpsteer issues. My understanding is you want them fairly close to the same length from one side to the other.

I verified that the pitman arm on the old vs new trucks are indexed exactly the same by looking at new parts from the LAPS. The pitman arm fits on the steering box by splines that have flats at the quarters, so the only movement available there would be 90*, which is too much, considering the total movement of the box is less than a half-rotation total. If I could move it a couple splines, all would be well. My thoughts at this point are the possibility of a different idler arm, or center steering link between the years. The LAPS website shows different part numbers for the idler arms, so there may be some difference there, though they are not splined, so I'm not sure how it could affect indexing.

FWIW, I also experienced this exact same phenomenon when I performed the late model steering box swap on my '72 Blazer. I 'fixed' it by yanking that crap out and installing a DM and R&P. This is no longer an option, as the truck fund ain't what it used to be...

Thoughts? I'm leaning towards the center link being different, but not sure where else to look if it's not...

Thanks in advance for any suggestions -Chris