Here's the dimensions for the cab support shackle holes in the frame.
My frame is in camouflage right now.
It still needs to visit the sandblaster.
There MIGHT be holes in the cab floor reinforcement shown in the photo you posted, but if not, let me know and I can measure those for you also. I haven't seen a '48 floor, which I imagine would have reinforcement in the center where the single mount is. Just a single thickness of sheet metal in that neighborhood on the later cabs.
