1966 Plymouth Valiant questions

The rear quarter spears are different on our 2 cars…both are 1966 2-door sedans, one measures 35 1/2” long and the one on the low mileage unrestored car measures 31 1/2” long. Years ago I bought a real nice piece of 66 trim, I cleaned and polished it up and when I went to put it on that’s when I noticed it was shorter…so I’ve seen a few now, I’m not sure why there are 2 different lengths?

6B2B5BF0-4D33-49F5-98F5-9C2BC9CAC0A1.jpeg

C0C8220F-31B5-4F3E-9D5D-91772A9AEDA1.jpeg

4E39E641-7779-49B1-98D8-3DF77E273FEF.jpeg

4DA35A36-DC15-4B31-9839-8565D005D076.jpeg