Maybe this will help. This was quoted for a '72. I'm getting ready to order plugs from MSA......here is what they quoted me yesterday. They offer 4 different sizes:

43.0mm Item 30-8001@ 10.33 each (largest spare tire area)

32.0mm Item 30-8003@ 00.93 each

25.4mm Item 30-8002@ 2.42 each (Floor Pan Plug 1")

25.0mm Item 30-8004@ 2.27 each

I ordered my plugs( 9 of them) from the Nissan dealer and they were 2.42$ a piece. They only had the one part # 77700-89914 and that was for the 1" plugs.