Besides the obvious, what's the difference?

[nvr2mny]

I have 2 different "defroster" types of rear window glass for a Targa. One has only the defroster bands in the middle of the glass (running horizontally) and the other with the bands on the whole glass, (also running horizontally). I've seen the ones with the bands running vertically, but don't have one of those. What is the year difference, if any?

[canamfan]

I'm not sure what year they're from, but I'm guessing the first glass (with lines in middle section) are a single stage rear defrost & the second pic glass (with lines all the way top to bottom almost) is for a 2 stage rear defrost, where a corresponding defrost switch, when pulled out once will turn on the middle section only @ first, turn the defrost switch, say, clockwise to second setting (while pulled out), & it turns on the whole element top to bottom. Now in some cases IIRC you can turn switch first then pull could intensify this /these actions for said elements or just the reverse action I forget the last part

[nineball]

finally! i have been wondering for a few years why my rear defrost not only pulled out but also rotated to another setting. even posted a thread on here about it and all i could find was that it had something to do with heated side mirrors, which of course i do not have. thanks.

[Nickshu]

There was also an optional heated windshield option that was activated when the defrost dial was rotated right. My 82 has it, but the windshield has been replaced with one without an element. Took me several years to figure out what the "mystery relay" was for under my hood.

[nineball]

weird. my windshield is original but it is not heated.