Someone asked me this a while back when looking at my car. Copying my response post from about a month ago...
Did a little research...
From 75 FSM. Here are the wires going through grommets. What is really strange - in 74 book the blower and compressor switch are same as pictured here, but the oil and temp go through the bulkhead. Then in 75 they take 2 wires out of the bulkhead and through a grommet. In 76 FSM, they are all in the bulkhead connector.