Should new carpet have factory holes precut?

No, the flooring is just the basic shape and size you need. It's up to you to do the final trim and the holes. I had to do this with my 94 TCD 2500 installing a new floor. It was vinyl, but the process was the same. I got it good and warm in the sun for a few hours, then laid it in place. I started at the rear of the cab and from underneath, stabbed a heated awl through the first few holes I needed to anchor the flooring. Then my buddy held a 2x6 block under the marked holes while I used a HF hole-maker to pound through the vinyl to get the hole for the seat belt anchors. If this was carpet I would have singed the edges of the hole with a flame so they would not unravel. Once these holes were anchored down with bolts and fender washers, I could continue forward knowing I had a stable base to work with.

Once the first few bolts were holding the floor in place, I moved forward trimming as I went to get a close, but SLIGHTLY OVERSIZED trim of overall size. Far better to give it a final trim than find out you went too far the first time. Don't ask how I know this. :eek:

When the initial oversize trim job is done, you can feel for the holes needed from inside the cab, but I prefer to do so from underneath so I don't miss anything. Any screw hole like for the shifter can be marked with a matchstick through the hole once the awl has marked the spot. Then, use a heated awl to singe the hole and you're done. Trimming the 4-speed shifter hole can be done by hand, just feel for the outline of the hole and trim with a razor knife, then singe the edges. When the rear of the floor was secured I started in the center with my 4WD lever hole so I could work outward to the doors and firewall from there. In my experience, carpet isn't a tight glove hit, it's a respectably decent fit but you will likely have to massage it into final position. Take your time, and a second pair of hands is very handy. This can be done solo but it is much faster and better with a helper.