I am currently restoring a 1966 Hipo Fastback, August Detroit build. My question is did Hipo's after 12/65 have the exhaust manifold lock tabs. NPDs catalog offers only reproduction exhaust lock tabs b4 12/65. My car did not have the locking tabs when I purchased it 40 years ago but they could have been removed years ago before I owned the car. I could not find any information on this subject in the "Library". And Tony Gregory's book "The High Performance Mustang", doesn't discuss this subject. So, no exhaust tabs or does it use exhaust tabs that just aren't being reproduced? Thanks for the help.