This is the plug that is used on the brass T-fitting for the 1959-1964. This is for the smaller 1/8" port that is used on 1959-1964. uses 5/16" plug There is a larger T-fitting port that was also used later in 1964 with a larger 3/16" port. Plug is 3/8" for larger port. Measure what you have prior to ordering the plug, or ask questions.