what is the recommended procedure to clean and hopefully preserve original markings such as this orange mark (looks like a grease pencil) and the more typical yellow paint marks?
Disassemble the whole trans. Soak the main case in Evapo rust then oil the surface and reassemble
But many will just take a bunch of pictures, even a tracing, restore the trans and reapply
Depends if your trying to restore or maintain/preserve IMHO