What is the correct speedo for a SS396 car? Do they vary from others or are they all 120mph?
Standard 120mph one for all cars except 427 Copo sports package.
COPO# 9737 (sports car conversion) in 1968 and 1969 included a 140 spedometer and a few other goodies. In 1968 Yenko ordered cars under this # and then converted most from 396's to 427's. In 1969 he ordered what is referred to double copo's 9737 and 9561 which included the L72 427. William published a nice report on the copo process which is under the reports section of this site. Other dealers ordered double copo's as well in 69.