The stenciled markings on the frame of my '31 sedan are somewhat hard to make out. From what I can tell, they read "AOS 5/28/31 N-4 SP". If anyone knows if this seems correct or not, please let me know. I understand the AOS is for A.O. Smith, the frame manufacturer, and the date is self explanatory. I'm just not sure about the N-4 and the SP. Picture attached. Thanks.
--------------------------------------------------------- Thanks much, Ralph "Roll Tide"
The 1931-2 frames that I have that still had readable frame stencil markings are the same format. I have assumed that the final letters and numbers identify the frame type and/or application. My '32 1/2 ton truck frames have "N SP" without any numbers after the "N".
