What is it?

So my windshield was broken and I needed a replacement. Called Ins. Co. filed claim. Glass guy called me and asked about car. I told him I had a 1972 Plymouth Duster. He said by the Vin number I had a Valiant. He stated that there was a difference between the Valiant and the Duster windshield. He said he would bring out the Valiant WS. He brought the Valiant WS out and it wasn't close. The A pillar was different angle and the length was wrong. He said according to my Vin it should taker a Valiant WS. The full Vin number is, VL2962B210511. Looking at the decoder it first appears that the Vin is missing one or two numbers? The V stands for Valiant. L= Low end. 29= 2 door sport coup. B= 198 2 BBL 6 cylinder "G" engine. 2= 1972 and I can't tell what the 10511 represents? There is No fender tag. I had read somewhere that there should be a number(s) stamped on the underside of the deck lid pass side that would give all the codes? Found nothing.... I have all the receipts for the car and some had phone numbers of the previous owner(s). Talking to the guy who purchased it from the original owner he said. (he has since died). The original owner was an engineer for Chrysler and was one of the engineers who worked on the PT Cruiser. He got the car when he retired in 71. It was either a prototype or an early model? It only had 9 miles on it. It was in a show garage with a number of other Mopars. After this second owner purchased it he started making changes to the car. i.e. new upholstery, wheels etc. I am now the fifth owner.... Q- How can I really tell what model this car is in order to get the right WS? VIN.jpg