Flashed, basically the dimensions are 18 tall by 64 wide or thereabouts. I had already installed it when I saw your question so I had to kind of estimate how much was tucked under the side panels. These would be a great carpet for older trucks because they are rubber and jute backed and have five clips along the top for easy installation. Just drill five holes and snap it into place.
I started off by pressure washing the carpet to get it clean then hanging it over a fence to drip dry.
And here is where my OCD caused me a lot of trouble. The upper center molding is held by 5 clips, the dome light, and one screw on each end. It would have been plenty secure with just the clips and dome light, but the screws on each end are covered by the B post trim, so I had to completely strip both side B posts back down. Out came the lower storage tray and jack stuff, both seat belts, coat hooks,and a bunch of screws. A lot of hassle, but I just needed every single screw and clip there to sleep well at night. I figure General Motors didn't put a single unnecessary screw or clip in these trucks. If it's there, there's a reason for it. While I had that all apart I also swapped in some real nice used door seals that came off a wrecked truck. My old ones were split and torn in some areas.
My phone plays tricks with colors. Sometimes it looks red, sometimes brown, and sometimes purple. Regardless of the pictures, it looks good and sanitary.
Note the rear wall carpet pieces seem puffy. It's not just a weak install job. The rubber backing and jute causes it even on original installation from GM. My brand new 94 Silverado looked like that sitting on the lot.
And I also clamped, cursed, and glued the passenger arm rest back into a shape that resembles what it's supposed to. No where near nice, but it's an armrest.
Other than buying floor mats and a driver armrest, the interior is now complete. I'm no where near happy with my door panel solution, so I'll always have my head on a swivel trying to turn up a better pair whenever fate chooses to bless me.