Can I use PXI-1 existing cards in the Keysight Card cages and are there any that will no longer work?

Older PXI (PXI-1) modules (which have a J2 present) will not work in Keysight 18-slot PXIe chassis. It may be possible to modify the PXI-1 module to work in the 18-slot PXIe chassis by replacing the J2 connector with an xJ4 connector. Per the PXI specifications, when a J2 connector is replaced with an xJ4 connector, most of the local bus lines are no longer available. However, few modules have used the local bus.