Cut the tip off of the passengers grommet from under the hood. The dimple you are talking about is a hole. I thought it was a dimple when I looked, but it's difficult to see in such an awkward position lying on your back on the floor board, but it passes through. I used some 14ga wire as a fish. Push out from inside of the truck and pull it on out from under the hood. I used some hand sanitizer as lube when I pulled 4ga cable and it worked great.
Did you get your kit? I ordered this with an lc4.800 and took a month to get it, several phone calls, and one PayPal dispute. After install, I had to switch 2 speaker wires from 2 channels as the harness was wired incorrectly. Following to see how yours ends up.
I'm about to replace the front set with the Kenwood Excelon kfc-xp6902c. I will let you know how it sounds. It comes with their replacement 2 3/4. Probably the same one you saw on crutchfield. The KFC-6903c comes with a 3.5 inch and says it's a replacement for Dodge and Toyota but the shop is recommending I put in that kit. They will mod the hole for the 3.5. It costs the same and you get a better speaker. They are doing a Trail Boss now with the same setup so I am going to listen to it before I have mine done.
Can you tell me which radio option you have on your truck? I just picked up my Trail Boss and it sounds horrible. Mine has the rpo code of IOR, which is the most basic radio from what I can tell. It does have the 8" screen. I was thinking about the Kicker kit but was wondering how your Alpine turned out, and what head unit you are pushing it with (IOR, IOS, IOT, IOU). I will be following.
Just picked up my 2019 Silverado yesterday and found the radio to be horrible. Tried adjusting the bass, mid, and treble with minimal effect. Thinking about the Kicker upgrade. Does the Bose radio have the HD radio function? Mine does not but it looks pretty easy to upgrade from Infotainment.com for $700. Just wondering how the subwoofer would sound with an analog radio signal vs HD before I buy either one.