For example, a Cobra kit-car using a 1968 351C Ford V8 would require all emissions equipment originally required for that model year engine.
A dune buggy upgraded with a ''91 L79 TPI GM V8 would require all emissions equipment used on that engine.
More generally, if a configuration precedes 1966, no exhaust emissions controls would be required.
If the configuration precedes 1961, no PCV system would be required. If a range of model years applies to any particular engine configuration, vehicle owners will have the option to select the model year of emissions controls to be used.