Rear window interchange years

[HAFROD]

Guys, working on my 80 Regal 2 door. I've located an 86 2 door Regal rear body shell with rear window defog. Will the rear window from 81 to 87 fit 78 to 80 2 door cars? I'd like the rear defog for winter. I can get harness and switch with it for $40

 

[pontiacgp]

yes it will fit, the books say the earlier years are not compatable with the later years but that was only due to the 3rd brake light and the defrost lines were not permitted to "block" the 3rd brake light. The defrost lines go around the 3rd brake light.

 

[Rktpwrd]

Yes. All back windows from 78-88 will interchange with the exception of the aerocoupe cars. (Obviously)

 

[HAFROD]

Thanks guys. I thought it would be cool to use the 3rd brake light as well

 

[pagrunt]

Just as pontiacgp statedwith the third brake light openning with the heated glass, it'll be all '78-'81 A-Special (x37, x47) heated or non-heated & '82-'88 G coupes non heated, '82-'84 G heated.

 

[spidereyes455]

Here is the listings right from Hollander. As an FYI 2 and 4 doors are different, and obviously so are wagons.

 

[JAMCAR223]

Someone show me a heated ( defrost ) rear window for a Cutlass Aeroback...

 

[spidereyes455]

Ask and you shall receive. It does exist but if you'll actually find one is a different story.

 

[Olgambler84]

yes it will fit, the books say the earlier years are not compatable with the later years but that was only due to the 3rd brake light and the defrost lines were not permitted to "block" the 3rd brake light. The defrost lines go around the 3rd brake light.

What’s the reason for the lines not permitted to block the light? Asking because I acquired a a 3rd light from a donor car and don’t want any issues

 

[69hurstolds]

What’s the reason for the lines not permitted to block the light? Asking because I acquired a a 3rd light from a donor car and don’t want any issues

There's no legal issues with it at all. Windows will physically fit, but the grid line will have a "hole" in it if you use an 86-up rear heated glass without the 3rd brake light installed. And if you use a 3rd brake light on the 85-below heated glass, try and not let the rubber lip touch the grid lines if possible. The grid still will work, but the rub is (pun intended) the rubber lip on the lamp is really there to block peripheral light from the 3rd brake light from diffusing on the glass and reflecting back into the cabin so it works best when it's actually touching the glass to block any reflection. But with that, the rubber lip could rub up against the grid lines and eventually cause a service issue. Hence they changed the grid line routing for 86 and up as to not be in the way of the mandatory third brake light so it sort of wraps around the brake light. Up through 1985, the grid lines for heated glass go straight across. In 1985, the third brake light was actually an dealer-installed option for GM so that should allay any fears of any legal requirements. Now the legality for the manufacturers may have had something to do with it, but not if you installed it. Same pieces/parts as the later factory versions. They were trying to make a buck off customers with the then-new regulations coming into play for the 86 model year. I used to have one of those 3rd brake light accessory kits in the box. The instructions said something like the rubber gasket may need to be trimmed to fit the back window. I never seen me ever using it so I sold it many moons ago.

Up through 1985 grid lines:

Here's a page out of the 1985 Cutlass brochure on the options and accessories pages...right in the middle...

I couldn't find a pic of an 86-up glass itself with the gridlines, but if you look closely at this pic of my 87 442, you can see how the bottom 3 gridlines drop down when it gets to the area around the 3rd brake lamp;