Hi, I got the following info from the old Yamaha archive back when I first got my FG-500. The label is red. The truss rod cover is the silver and black one like the second one you posted. Sorry, but I couldn't find that mysterious internal date code, but the date I have is based on the info that Yamaha had up on their old site. In addition to what follows, might I add that this is an amazing sounding guitar.
Yamaha FG500 Serial Number - 20408187
Made April 08, 1972 #187
Year(s) Sold: 1969-72
Original MSRP (US$): $320.00
Top: Solid Spruce
Back Laminated Jacaranda (reputedly Brazilian Rosewood)
Sides: Laminated Jacaranda (reputedly Brazilian Rosewood)
Neck: Mahogany
Fingerboard: Ebony
Bridge: Ebony
Body Depth: 96-116mm
Color(s): Natural
Finish: Gloss
String Length: 637mm
Included Accessories: HSC
Notes: Hand Crafted