It seems as though I had a misunderstanding that was increased with the very first reply I received.
This post is what got me to re-look into this:
1st design 26016461* The original was a 2 piece design, I believe the revised design is of a non-seperable one piece design. both with 2 hole frame bracket.
2nd design 26059031 does not apply and is not the superceeded part as it's for 93 up and has a 3 hole mounting flange. A completely different design that won't bolt up to your frame.
This one really rang with me, so I looked into it:
This is the design of the part #26016461 for 1988-1992 trucks:
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This is the design of the part #26059031 for 1993-2000 trucks (as per post #2):
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These are CLEARLY
not interchangeable, so although they do qualify as first design and second design, they don't fit within the context of my original query.
So that right there was a HUGE derailment from what I was asking.
I could cite many examples where GM revised a part so that functionally it worked to replace the original design part, but while the changed part was first installed on later model year vehicles, it then later became to the superceded/replacement part for the earlier vehicles;
That is the type of "first design vs second design" part that I was inquiring about.
To the best of my recollection, the mechanic told me that the design of the replacement idler arm wasn't exactly like the one he removed.
To be quite clear, camber and toe are perfect.
You do not need to put a vehicle on a rack to check this - racks are a newer innovation, and I can assure you that alignments can be done without any newer tools;
This replacement idler arm has in some way geometrically deviated from the part removed from my truck and has pulled the center link to one side, making the steering wheel not straight when the vehicle is tracking straight.
I stumbled on the following discussion last night when looking further into this, and believe it has bearing here;
It cites an example where an aftermarket idler arm does not actually mirror OEM specs:
BEWARE MOOG IDLER ARMS
After some back and forth which seems to make a pretty clear/convincing argument that (in this case the third gen F-body) idler arm is often manufactured incorrectly (maybe due to quality control at different facilities - who knows) this is posted:
Just spoke with a technician at moog and explained to him the issue with their idler arm. I told him I have pictures and everything showing how it's a wrongly designed part, and he basically told me the cars are too old for them to bother redesigning it. I asked him if there was anybody higher up that I could e-mail the pictures too and that it was pretty apparent from them that it was incorrect, and he said that they wouldn't do anything anyways...
It doesn't seem to be a huge stretch to think that the part which was installed on my truck, although a correct replacement part, has something off about it which alters the geometry where it should connect to the center link compared to the GM part removed from it;
So, my initial query where I stated that:
(he) told me the design had changed from the original part
I had interpreted that as to understand that the design had changed.
Then when the first reply to my query was:
We did a design change on those and the 26016461 has been discontinued and removed from all aftermarket and OEM sources since 2002. It was replaced by the updated design of the 1993-2000 # 26059031.
I saw that as an affirmation of sorts - hopefully some of you may understand this.
The following are the part numbers are ones I have found, which may or may not indicate a revision to the original designed part (sometimes GM has seemed to arbitrarily renumber a part; I have understood that sometimes this is an indication of using a different supplier, while other times something has changed in the design of the part):
26016461
12387682
12471302
88911352
I do not know if all those parts are put side by side (these are I believe all GM numbers), if they would be exactly the same - but they do indicate a change of some sort.
I still hope to remove this aftermarket idler arm for a GM part which should hopefully prevent me from having to screw with my alignment.
If a member of the moderation or administration team wishes to delete this discussion all together I will completely understand.