Reply to "Passenger side engine cover"

Otis; According to a TSB published in March, 1974, the right engine cover with a hole to access the expansion tank was introduced in January 1974 effective with body #52426. While its common to refer to the last 4 digits when looking at serial numbers, the TSB references 5 digits. The hole was to check coolant in the expansion tank instead of the pressure tank to eliminate the possibility of eventually ruining the pressure cap seal. Since you mentioned later serial numbers, a number of build dates and serial numbers have a way of not matching.