Vin number confusion

Hey everybody. Was trying to decide the vin on my challenger today. I can’t find the 13 digit number anywhere but there is an 8 digit one stamped on the cowl and radiator support. It reads p4338127. Not sure exactly what everything means maybe one of you guys could help me out? The p might be an r which means it has a hemi (yeah!!) but that didn’t exist in 74. I was told the car was a 72 when I bought it. Any help is appreciated.

thanks

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