i put a third row in 01 with barn doors and i got a carpet off ebay. The color, fit, padding and plastic for the 3rd row were exact factory match, i didnt trim anything. I don't remember how much but i prob still have the ebay stuff, i know i still have the stock carpet so i should have the name and bill stuff. I used ACC for an 81 monte carlo back in day, i def had to trim that. Ill look for that company info sometime today.
Edit**Place is still in business on ebay but i checked no carpets, i guess it was longer then i thought....i did the swap in '04....Weird place though....says new and used parts....carpet i got was brand-new and fit and matched perfectly it even had that new carpet smell....whatever. Im f'in rambling again, long day. Nordstromsautoinc....