Merry Christmas everybody. I recently purchased a Bridgeport J Head mill. It does not have a DRO. So, after doing some research, I've decided to go with the DRO PROS EL 400. I am debating to either go with the 3 axis or 4 axis scale model. I definitely want the quill readout. When I spoke with the folks at DRO PROS, they said that I could easily use the z axis scale for the quill readout and they would substitute the brackets accordingly if I went with the 3 axis. I am just a hobby person and still in the learning phase. The difference in price was around $200. Buy once, cry once. Not sure if the z axis brings a lot to the table. What I like about the DRO PROS, their quill readout is part of the DRO. I am not wanting a self contained quill retrofit with separate display unit or at least I don't think I do. ?? Thks