those pipes sure look like M/T tri-y's. i had a set on my charger, although they were for a big block. 1 3/4" tubes, and i bought them new in around 1973 or so. i didn't like them because starter access was a pain, and it was also fun getting the transmission pan off.
i traded them off many years ago to someone for a bigblock truck oil pan setup.
i can't tell you how many years those were made.