I dont know what a York is, but the adjustment I was speaking about is physically on the PCB that plugs into the back of the CRT, known as the CRT neck board. this control is called H-STAT, or otherwise known as Horizontal Static Convergence. it adjusts the potential to ground one of the grids in the CRT which affects horizontal convergence alignment. When I saw one of your pictures after you put the new board in, I knew right away that adjustment needed tweaked.
There have been a number of discussions, in detail, on this very point.
Basically, the early PPC750's which have pins to support external L2 cache are all pin compatible. They may require different voltages, or configurations on some signal pins (PLL configuration pins, e.g.) but the balls are in teh same place.
The PPC740 is different, because it does not have the capability of supporting an L2 cache, so those pins are not present and all the pins are rearranged.
The 750CX adds a 256K on-board L2 cache, and so again, the external connections to control the L2 cache are omitted so the pinout changes. However, the 750CX is also not compatible with the 740 pin arrangement, although it seems like it could have been. Perhaps they're in different size packages, I don't remember. They are enough years apart, the process technology for the die could have changed and so the package size may be different as well.
The 750FX and 750GX are compatible with each other, but are a change from the 750CX for some reason.
So, for example, if you have a PPC750 with external L2 cache support and want to replace it with a later model that moved the L2 cache on chip, it will not be an easy task because the pin/ball arrangement changed.
Well with the 1.6mm it is possible to get them in there, I just wouldn't recommend it. You have to kind of put it on top of the socket then rock the simm back and forth until it goes in. It might be a good option if you never want to take it out again, but taking them out is really scary lol
The boards need to be 1.27mm thick. The original spec. is for .050", which is 1.27mm. There's some +/- in that spec, but really not enough to go to 1.2 or up to 1.6.
1.6mm is .063" thick board, which is far thicker than .050". I'm amazed that you could get it into the socket at all.
I posted some datasheets for SIMM sockets in an old thread, which included the specs for boards that fit into the sockets.