I am interested in an early '73T. I asked for the engine number from the seller & this is what he sent: 9011061015R .

Is this really the engine type stamping rather than actual engine number (it doesn't seem to resemble red book info)?

Could the '5R' at the end of this number indicate its not the original engine (73 is a 7R case correct), or is the info meaningless?

thanks!