Did all cars come with factory undercoating or was that a dealer installed option? I'm not talking about the wheel wells, I'm more interested in the underneath. Is it coded on the buildsheet somewhere?

If you know could you please elaborate on the details of where and how it was done?

Thanks, Rob

It was a factory option code J55 on buildsheet. The factory did it after most components were installed like brake/fuel lines and fuel tank, etc. My Challenger vert was undercoated only on the drivers side, someone was asleep on the job back in Sept 1969...I know the trend is to primer restore without undercoating but most original cars I have seen did indeed have undercoating although my Duster is bare.

And, if equipped with a fresh air hood option, just the undercoating

would the J55 be on the fender tag also?