Doing a batch of relay boards when I came across this one. Top looks normal and has a stamping 01 90, so I am assuming it was made then. Any way the back is completely different. There are NO deep groves or vacant pockets. The copper strips are just barely lay in shallow channel, probably how the original ones should have been made. Very clean. Hard to show but look carefully at the pictures.

I had one made in 1986 but it had the deep traces.