Factory markings and codes? HELP

i have a 72 demon 340 i m currently restoring. i wanna put the factory markings back on it. i ve found a lot of them when i tore it down. there s a partial painted 3 digit # on the axle tube, but there was a rusty spot over the first number. i need a good source for reference photos, and or code meanings. i ve googled for hrs. and nothing.
i figured one of my fellow A-body guys would know what to do........so i m leaving it up to u guys, and gals. thanks for the help.