Honestly, did you expect finding sheffield gray dash/console pieces were going to be easy? After the first 87 442 left my possession when the first wife left my possession, I never had another until 2007, so I never had a need until then. So far I've scrounged up all the stuff except for the passenger dash vent panel.
GM seals are the BEST, hands down, for fitment and durability. But obviously, that's the rub. The newest ones are probably 15-20 years old or more. Some they haven't made in a good while.
I can tell you, when you bought seals from GM, if they came in a box, they were just twisted and crammed in there to fit because likely, they thought the box just needed to get to the dealership and the dealer would unpack them and put them on a car that need them. Same with the ones in the peel apart packages. Just fold them, seal them up, and send 'em. Because they don't ever consider Joe Customer would simply buy them for his own project 15 years or more later. So even if you find new GM seals (and usually you will pay dearly for them), there's a chance they're already screwed up. Not always, but there's a chance. Especially T-top seals. Sheesh. I've been pretty lucky so far in that all the seals I've got are still soft and supple. Again, it's a crapshoot.
As far as aftermarket seals, I don't know who makes good ones. Soff Seal I thought was a good seal, but they seem a bit too dense for me, and hard to "form" in order to seal well.
I've also heard of some aftermarket T-top glass seals to pillar seal contact areas come up a tad short leaving a friggin' gap! That's no good either. Oh, and at least at the beginning, one of the manufacturers were trying to use the wrong ends on the door seals for the Cutlass/Regal. I think they just tried to pass off Monte door seals, not sure.
I'm the last one to ask about aftermarket weatherstripping. I try real hard not to use that stuff.
81-88 Cutlass/442 GM part number listing:
Trunk seal- this comes in (maybe, I've seen a few them arrive unglued as well) one piece already glued together and has the paint dot that goes in center front to help with alignment, as well as the "cut your own" one long length of strip that you have to cut the female side of it at the back to the proper length, then glue the male tab into the female slot yourself. The one piece is ok, you just have to loop it over the trunk lid if you don't want to remove it. It will go. I used it on my 84
H/O (before reinstalling the spoiler, obviously).
1-piece- 20641957 superseded to 25558394
cut your own - 20490800
Interesting that the 20490800 was listed to fit the 70s Nova hatchbacks, etc., yet also listed to fit G-bodies as well. Weird things GM did.
Doors -
RH- 20201220
LH- 20201221
Belt reveal seal (along top of door) -
Thin bead outer
RH- 20674248
LH- 20674249
Wide molding belt reveal- comes with weatherstripping attached. (Not used on 442 in 1987)
RH- 20674292
LH- 20674293
Seal only- to fit wide anodized (chrome) molding:
RH- 20674276
LH- 20674277
Inner door belt seal, (on top of upper inner door panel) same for all G47 Cutlass
RH- 20363106
LH- 20363107
T-top -
RH- 20211820
LH- 20211821
T-top glass side seal -
RH- 20087982 superseded to 20217186
LH- 20087983 superseded to 20217187
Secondary T-top seals (stick on strips- aka "rattle strips". Usually come unglued and get missing)
Need 2- same part number- 20139617
