I'm not sure whether it was answered -- yes, you can fit a blue 3PDT into an MXR box without any problems. I was looking at my '78-ish D+ vs. a 1590B and a taiwan B box. The extra 1/16" depth is all in the bottom lid, oddly enough. Years ago, I added a DC jack and LED at the top of the box. Today, I would try to move the LED down below the knobs and see if the DC jack could fit next to the 3PDT...that seems more standard.