Has anyone yet installed the D3 into a 2008 GMC Ext Cab SLE2 3500 dually that comes with the factory audio system? If so please comment.

A more specific question or questions would help. Are you trying to decide if you can do this yourself, or is there a specific problem you're having? Also, is it any different than a 2500HD? I know the truck itself is different, but would the install be?

tractor4u installed his own in his, so I'm sure he may have already cleared up some problems that you might run into. Read his posts...i think there is another one about a specific problem with Source Level Adjustments, but otherwise, the install shouldn't be too bad.

http://www.avic411.com/forum/viewtopic. ... highlight=

I had gotten onto Crutchfields site and put my truck make/model information into their form and it stated that the AVIC-D3 wouldn't fit. I e-mailed them to find out why and haven't heard back yet. I do want to install one and I may or may not do it myself?

Do you know that your OEM unit is double din? How deep is the opening? Maybe their site just isn't updated for the 2008 models.

Yes it is 2 Din. Below is the answer from Crutchfield now I know why some have had to trim a little plastic at the rear of the mounting area for the install.

"Thanks for shopping the Crutchfield website.

I’ll be glad to help with your question about upgrading the radio in your ’08 GMC Sierra. According to my database, the AVIC-D3X is indeed not listed as a recommended fit for your truck. It seems the available depth in the radio cavity location is the limiting factor.

The installation depth available in your Sierra is about 6.74â€. The installation depth of the AVIC-D3X installed in your truck is about 6.88â€. The difference is about 0.14â€, which of course isn’t very much at all. Additionally, we factor in about ¼†to ½†depth so the wiring harness at the back of the receiver has enough room. Given all of this, the AVIC-D3X should fit your vehicle – but you’ll just want to be aware that this depth issue is the reason that we don’t list it as a fit. I hope this helps".

That's why places like CF and tirerack are in business....they test EVERYTHING before they say it fits or doesn't.

Can you modify the back of the opening in any way?

I know I could. Remember that no matter how committed you are to your car (I'm practically married to mine) that it is still just a collection of parts made of metal, plastic, glass, wire, etc. You can use a dremmel and cut out the plastic backing, just don't cut any wires. If you are at all nervous, I would recomend going to a pro and let him do it. 1/2" is really nothing.

I got some good info from the forum on Dieselplace about what needs to be done to have it fit. They just use a dremel and cut out/grind out a couple area's in each lower corner and back center that are plastic. Actually very minimal.

Circuit City said they would do the install even if I buy the unit and accessories fron Crutchfield if I decide to go that route. I have worked as a mechanic and have all the tools.