When was the firewall carpet guard, # 3916615, added?

[CantRepeat]

Is there a known time frame this part was added?

Was it only with deluxe interior or standard as well?

My 11B doesn't appear to have the firewall drilled for it.

[cook_dw]

Mid/late year changeover IIRC.  Across the board changeover when it did happen.  Some report as late as 04D with no guard. 

[philip]

My 11B  didn't have it too