OBD1 is very very generic. There really are no start years associated with it as far as I have been understanding it. It ended in the US in 96 when everything was mandated to OBD2. Quite a few cars had OBD2 earlier, but it was not quite as comaptible. Some fords for example had both connectors, OBD1 under the hood and OBD2 under the dash, but only one would work. It is pretty much from the time your car company decided to read codes thru a connector or by flashing out a signal with the MIL lamp.