Hi,
WMMT3 and WMMT5 do not use the same boards. WMMT3 is still on the old namco design with STR2 FFB.
WMMT5 is on the new design with STR3 PCB. The I/O and basically everything is different aswell.
I'm currently working on trying to get the newer versions working in old cabs, but i don't have a lot of spare time to do that.