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136371R138995
1= Chevrolet
36 = Malibu, El Camino* (Custom), Concours, 8-cylinder
37 = 2-door sport coupe
1 = 1971
R = Arlington, Texas
38995 = Sequential Production Number

Nothing in the vin will ID it as a SS Model in 71, in 72 if the VIN has the letter "W" as the engine designation, the car had to be a Z15 SS-optioned Chevelle. While there is this change, Fisher Body Number plates still showed no indication of the option. Engine codes in the VIN were "W" for the LS5/454, "U" for the LS3/402, "J" for the L48/350-4, "H" for the L65/350-2, and "F" for the base/307-2 engines -Could not be ordered with the SS option.
The SS package was an option from 69-71 you need paper work to document if it is a true SS . SS Cars 66-68 down started with a vin of 138.

Sounds like you got a good deal on your car. As said above pictures.