@fourfive
@3bears
@JZiggy

I think? maybe this has something to do with the fitment issues? I have noticed there are a couple of different tube nut configs, they are also designed to work with a very specific female connection.

if you look at the pics, all of these are OEM Toyota tube nuts. you can see the first pic has a collar before the threads start. these are generally used for longer runs and union connections.

the other pic shows a type used on most calipers or cylinder connections.

some of the aftermarket parts are made to work only with the non collards connectors. they have a much shallower female socket so you can't even get the threads started. I had to swap out flange nuts when I did my rear disc brake conversion because the mustang flex hoses will only accept the non collared tube nuts. I think this is exactly what is being described here? toyota thinks your going to use their flex line and it's going to have a deeper socket for the collared tube nut. wheelers maybe missed this detail?