I learned in this forum where the original VIN numbers should be.
However, in 1981, when I sanded down the frame of my M715 I found noting in the locations mentioned. In the diagonal cross member supporting the trailer hitch I found numbers on both sides. But they did not match the sereial number mentioned on the plate on the dash.
I know from other people in Germany that they found on the locatins mentioned some very poor stampings which for them happily matched the dash bord plates.
I stamped the serial number in the right side of the frame by myself. And it was good enough for erveryone due to the knowledge in Germany that US vehicle serial numbers are not neccessarily stamped into the parts required by German requirements. I still own that truck
Wolf