Tried looking this issue up in both archives with little success. When I bought my '79 308 GTB over a year ago, I liked the black lug bolts against the OEM 14" wheels. Little did I know. Found out recently from my mechanic that they are aftermarket lug bolts that are all 5mm too short! I have had numerous "spirited" runs with the car and he said that the wheels could have easily come off! ARGG, not for the faint of heart. I have now ordered replacements from Hill Engineering. My question, how critical is 5mm anyway? My mechanic sounds desperate but I have put over 1,500 miles on the car since purchasing with no ill effects. I appreciate all technical input.