[PxTx]

I was not aware of the sun gauge faces being year specific. I have seen SST prior to 1968 with both blue and green faces. In 69 the blue 2 5/8" were most likely available.

My guess on the Otis car was that the Green gauges were chosen to compliment the green car. That is where the no tach problem came into play. I can only speculate this, but here goes:

I have not seen an integral SST with a green face. I would imagine that the original owner of the Otis Camaro wanted to have a tach that matched his gauges (being the car is so pretty why have a tach that clashed). When all that Joel had on the shelf at this point was blue SST- Joel most likely offered the hood mount tach as a reasonable alternative. Maybe not- but this car is definitely before Joel clearly figured out which tachs worked best with the "new" (at the time) CD ignition systems. Maybe Joel had a green SST with a transmitter, but the CD system generated too much EMI and the tach was bouncing all over.

I don't claim this to be accurate, just a reasonable speculation.