75 Duster Tetnus Shot and band aids

I'm decoding the fender tag and on the 4th line it has code M51. All of the research I have done the code keeps coming up as power sunroof with vinyl top Is this right? Car has hardtop
that's what all my lierature has also. stupid question, but does fender tag vin match car? seems very odd that you'd have a power sunroof code. also...if it was a sunroof car, it would've been manually operated (M52)