Looks line they would both function, Todd.

However, I understand your concern. When I replaced my failed brake line with a stainless steel braided hose (from Van's aircraft) it turned out to be a -4 line whereas my other gear has a -3 brake line. Both brakes function and stop the aircraft, however, there is a distinctive difference in the feel of the two brakes. The -3 side has almost a rock-solid feel, the -4 side has a slight bit of give upon initial depression - actually you have to go down on the toe just a bit more on that side.

My guess is that the greatly increased volume of the -4 line over the -3 line causes more pedal movement on the -4 side to build up the same amount of brake line pressure. I really don't like the two different feels and have a new -3 line to replace the -4 line.

My guess is your two different parts would probably push on the pad with the same force - however, from what I have seen I would think that the one with the recessed top would be likely to accumulate more crude that the other one. On the other hand, there could be a good technical reason for the recess - like perhaps less surface area to transmit heat from pad to hydraulic fluid - now that's one I could relate to. That's the only reasons I can think of why the difference.

IN any case, I think I would prefer to have both the same - probably doesn't matter which on you go with.

Ed A