Well think of it this way: if I have Indy trucks and I leave the stock the bushings last so long that if I were to replace them with the aftermarket 90A I would think the two are not the same because my bushings are already so well worn in. You're never replacing the stock with another stock bushing. No sane person takes a stock bushing and replaces it with the exact same hardness and color that makes no sense.
I was told that NHS used to produce stock bushings to put into their trucks in much larger batches than their aftermarkets. This is why the old aftermarket's used to be machined on one side. I got some used Indy's with fucked up stock bushings and when I swapped them I noticed they were also machined. Same with the pair of 149 I just bought. Maybe the move to China made it possible to machine everything?
As for DLX I always felt their solid color bushings were harder than translucent but when I rode Thunders the 90A all felt the same until they started making the trucks in Mexico and now their stock bushings are completely unrideable for me.
I get that no one is taking new trucks and replacing the bushings with the same ones. It doesn’t make sense that they would purposely make the replacement bushings for when your stocks wear out, different to match the feel of your old bushings because why not just make the stock ones feel “old” to begin with? If you want to end up with the same broken in feel, you have to start with the same new bushings.
The only thing that makes sense is what you said about the stock bushings made in different batches or sounds like separately altogether. You would think they could still make them match exactly but probably where my thought of profit maximizing combined with making them separately creates the variance we see in the products.
Re Indy:
I think a lot of the parts had established production lines before anything has been consolidated, which I guess it still hasn't, so for Indy, the aftermarket bushings are made somewhere, with the trucks being made and assembled somewhere else, with the smaller parts being shipped in to be put on the trucks, which has always been the case with some brands.
I did notice that the new Indy trucks coming out all had smaller / thinner washers on them, so it might have taken that long for the change over process to happen, if they were sitting on thousands of washers, bushings, or smaller parts to go on the trucks.
The Indy aftermarket bushings are different to the stock bushings, which have also changed over time, but maybe the thing with the washers that come with them, they might have made them smaller to fit into the clear plastic containers. Also the cylinder bushings do fit on the washers that come with them, but you just need to have the circle ends facing the hanger and the plain rounded end on the washers. I had thought they didn't fit either, but someone else had put them on and worked fine like that.
That is also a difference between bushings being poured, with the unfinished sharper edge top / bottom look, compared to the injection mold option which they have the circles on them and look way more finished on all sides and rounded edges on the smooth sides.
There are posts about it in the Indy thread.
Re Thunder:
I think the age of any product also has something to do with how bushings feel too, eg if older Thunders, or at least their bushings had been sitting around for years, whereas the newer ones have not, the newer bushings would not have had time to firm up or cure at all, hence the new purple Thunder inverted bushings (or the T-II bushings) said to feel way softer than the other colours.
The purple bushings (and T-II bushings) still firm up to be about the same as any other Thunder 90 duro bushing though - I have some on boards and have been testing them a lot recently, just to see. It just takes more time to break them in and have them firm up, but I also get it that some people don't want to have that break in time and want things to work right now.
Other things to note:
Some brands of bushings also have different countries of origin on the packets too, so it would also make sense that some are not going to look or seem the same as what might have come out before, because they are made in different places.
People have said that adding colour to urethane changes the consistency, so it makes sense too that some colours might not fare as well as others in how they feel, even though whatever goes in the mix to make the different duro options is well beyond my knowledge and information.