It seems that some people, who haven't built frames with them, misunderstand the difference between 135QR and 142TA dropouts. In order to help explain how the dropouts are attached to the stays in the exact same location on both, I have taken some pictures of one of my frames that was built for 142 thru axle.

This recessed slot is the only reason why thru axle hubs are 142mm wide. The slot is 3.5mm deep on each side, so the hub end caps were widened by 3.5mm on each side to allow it to self locate in the dropout, similar to a QR dropout.

The distance between the inside faces of the dropout is still 135mm, so the dropout attaches to the stays in the same location and the stays are the same width on both 135 and 142.

The distance between the faces of the dropout slot is the only thing that is 142mm wide. Obviously the outside face of the axle hole is wider, but that does not affect the placement of the dropout on the stay.

Good point, I know this but I might have posted some wrong information in one of the disc conversion threads. Thanks for the pics

You're not the only one. I've seen questions regarding brake mount locations being different because of the different width (they are the same, measured from the dropout face). I've also seen erroneous claims that 142TA allows for wider tires, have less crankarm clearance, etc. I just thought the easiest way to show how they compare is with pictures.

I've been looking at this same thing but for wider rear ends such as Boost 148, and Super Boost 157. I've seen specs on 157 having a 150 flange to flange width but nothing for 148. I would assume 141 for flange to flange, but I don't assume anything anymore especially with all of these "standards".

So far, there is almost always a QR version of all the different rear spacings. I just looked this up for my Mukluk, which is qr although it probably should have been TA. I think it's 7mm different with that too.

The same dropouts will be used for all of them and they have a 3.5mm deep slot for the end cap, so the spacing between the inside faces of the frame components will always be 7mm less than the space between the slot faces. The dummy axle width makes them compatible with whatever hub you plan to run.

Paragon makes very few dummy axles for 10mm. 135, 170, and 145mm.