When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
We've always called this a J nut. I assume you are talking about where the lower pad screws attach to the upper pad. This part was a standard part for GM and you should be able to purchase them at just about any auto body supply shop (Automotive paint store).
It's a 1 piece dash (79). They are the U Clips easy mike posted. The only problem is I cannot seem to get the lower pass anger side screw to go through the clip. I just left it going through the hole and it holds tight, is this alright? Also any advice on putting in speakers? Hard to drill holes for the screws under the windshield.
Just guessing.. I would say no, you'll need the clip in there. If you just have the screw going through the hole vibrations may force the screw come loose. With the clip this will not happen.
The speakers.. Oh.. you are supposed to drill the holes for them before you install... But.. not to worry..
You can use a self taping screw and sit the speaker in the pad, then if you have a 90 degree screw driver it's not a problem. If you don't have one, use a tiny ratchet and socket and put one of those screw driver extensions in the socket. This is actually the best way since you can push downward with the ratchet while you tighten it up.
Does the '79 have dash speakers? If not, then the dash doesn't have any mounting brackets/supports under the dash to handle the weight/load of those speakers...and unsupported speakers will likely cause the pad to fracture in time. If that is the case, you would do best to mount the speakers from the top-side of the pad and use/make some metal support pieces to fit on the under-side of the dash. Then you can put covers on the speakers to clean-up the look.
The 78-82 cars had little tiny speakers up front but they never seem to cause a problem when installed. They basically just sit on top the padded structure and are screwed to the pad.
Since the pad was designed differently than the 68-77 style it seems that is will hold these light weight speakers without issues.
Lightweight speakers [intended for mid/high frequencies only] that are mounted to the top of the dash should not be a problem to the integrity of the dash pad.
I only did that for 1 hole. It was the bottom passenger so if I need to ill try to get the clip in later. The dash has holes for 4 by 6 speakers with little plastic corners to screw into.