Yes to both.

 

they will interchange,the spoiler end caps are diffreant on a 79 to 81.

they are square where the 78s and down come to a point on the bottom.

 

End caps? Like, inside the trunk?

 

The corners. The middle spoiler (attached to the deck lid) is the same for the 77 and 79.

 

The trunk lid itself will fit fine. The holes for mounting the spoiler will need 'adjusting'. The '79-'81 spoilers were slightly different and the mounting holes in the deck lid will need to be elongated. Dimensionally, they are exactly one bolt-diameter off. So make sure you treat the area with a sealer and rust preventative and use a wide washer with the nut to secure the spoiler. Unless you want to go to the trouble of weld-filling the original holes.

 

Good to know Jim.

I dd not realize that the 1979-1981 spoilers were slightly different than the 1977 and 1978 including the mounting holes.

 

Me either. I thought only the corners were different.

 

I've been through that. Replaced my '80 decklid with one from '77. The new mounting holes go through where the outer skin wraps under the lip, so be very careful elongating those holes.

 

So you are saying the mounting holes are different but the spoiler is the same?

 

Nope - along with the change in endcaps, the center spoiler changed slightly. It looks the same but the mounting pegs got moved. So, to re-mount my '80 spoiler using a '77 decklid, I had to move the holes in the '77 decklid. The lid on my '80 had too much rot from trapping water and debris under the center section of the spoiler. Wish I had a pic in my archives - an image would describe better than words. maybe I'll take one this weekend for documentation purposes.

 

Ok. Got it. Learn something new every day.