Clamshel vents

The slots are for the bolts.  The hardware stays in the body and the grill can be removed and installed around it by just loosening the bolts.  

The exact shape of the opening has changed through time and generations and the grills are made to fit several different models.  They are designed to use with a 1/4" c-channel rubber that hides the gap and curvature.  This was very simply done because the manufacturer wanted a separate tooling charge (that was VERY expensive) in order to curve the grills and the bars between them and make 3 different versions.  Thus we came up with a "happy medium" that would work across the board, and with the c -channel rubber you cannot see the gaps.

Adrian, for my own Thunder Ranch Spyder, I purchased from @chines1 (Carey at Special Edition) the c-channel rubber he's referencing.  They fit perfectly, and in my opinion, nicely finish off the look of the grills.  I highly recommend them. 

@chines1 Thank you so much for the explanation! I did not realize those slots were for mounting them. Sounds like the c-channel rubber is exactly what I need and I need some mounting hardware as well. I'll reach out separately.

@Wulfrik (John) That looks great and is definitely what I need. Your car is stunning and I absolutely love the date-matched license plate. I've heard there is a way to register these as the year of the car they are emulating. Someone told me in Oregon, it's as easy as checking a box on the registration form but I haven't looked into it yet. Oregon is another state where you can use Date of Manufacture license plates and it goes a long way in making the car look even more authentic. I got a '61 plate for my BMW R69S motorcycle, not easy to find but it sure looks cool.

@Adrian Tayne posted:

@chines1 Thank you so much for the explanation! I did not realize those slots were for mounting them. Sounds like the c-channel rubber is exactly what I need and I need some mounting hardware as well. I'll reach out separately.

@Wulfrik (John) That looks great and is definitely what I need. Your car is stunning and I absolutely love the date-matched license plate. I've heard there is a way to register these as the year of the car they are emulating. Someone told me in Oregon, it's as easy as checking a box on the registration form but I haven't looked into it yet. Oregon is another state where you can use Date of Manufacture license plates and it goes a long way in making the car look even more authentic. I got a '61 plate for my BMW R69S motorcycle, not easy to find but it sure looks cool.

All you need is a valid number and these guys.
https://www.licenseplates.tv/utah-186.html

While not “completely legal,” I never had an issue with my repro plate.

That's a great option. The police seem to be pretty lax around here. Some guys I know just carry their valid license plate in the glove box and rock whatever fun plate they want

Here in Florida the state produces dozens of different styles of plates. I doubt law enforcement has an issue down here, but you have to have the registration sticker on it or they will stop you.

I think buying one of these just might be the ticket....

I mean be OK.

to continue the thread drift.... in Indiana you can buy an original YOM plate and bring it to the BMV and they will put it in the computer as your current plate, tied to your modern plate number.  If/when the police run your vintage number it references your modern tag number and is 100% legal.  You are supposed to carry the modern plate in the car and be able to produce it on request.

@chines1 posted:

to continue the thread drift.... in Indiana, (etc. and so forth)

That sounds like a typically “Indiana sensible“ solution.