I'm not sure how to add a photo as an attachment.
When you 'click' on the "Reply" button, you'll see a link directly below the main text box that reads, "Attachments and other options." Click on the link and it will display the attachment window with cursory instructions, including the maximum image file size of 256KB. If you download your image to your PC, you can then click on the "Choose File" button to navigate to the image and select it for attachment.
With no other brake code listed on the SPID, you may have to physically measure the rotors, drums and shoes, then take that information to a dealer to determine the RPO code. Chassis GVWR should be listed on the vehicle ID plate/label.