ford rear window defog in mustang?

i have a question of whether this rear window defog ever came out in the 70 mach 1. i have pulled a complete setup out of a ltd. the wires and switch and all. it is in super shape and was wondering if this could have been an option for this car. they go for big bucks on ebay and was worth the effort in getting either way. it has a speaker-like grill cover with a fan motor under it.

Hello!

I never seen a window defroster on 1970 Mach1.

Ray