This is an interesting inquiry in that I expected to consult one of my lists and find a simple answer - well it ain't necessarily that simple. The EMPI catalogue gives an excellent break down of chassis codes and engine numbers but " AD " does not exist there at all ! I found another printout of a page from VWBeetle.org and they show the missing AD code and the missing AC and AB ones as well. The latter two are for the 1.3 litre which never came to North America during those 1970 to 1975 model years. The list shows the AD as a 1.6 litre from August 1970 to July 73 for type one and type two VW. Is your car European? I'm betting that it is and that the AD is likely a European 1.3 as well. EMPI may have not bothered listing them as they are likely hen's teeth over here. Any other lists out there? Dan (MY72BUG - which is an AE) in Goderich, Ont. Canada
I'd rather have a partial bottle in front of me than a partial frontal lobotomy.