[joyridin']

Well, since nobody replied...

My car has that shape. From what the original owner told me, he bought one of the last Arntz cars made. He raced it for a few years, then took it to Butler and had a complete interior installed. So mine is a bit of a half breed. Considering the Type 4 had this notch, and the very last Type 3 models, I would assume it was near the end of Arntz production. I think if you dig on here, one of the guys stated that Butler had the Type 3 molds without the notch.