I have been searching for a replacement for the driver's side seat bottom on a 1999 regular cab SLT 40-20-40 seat for a couple of years. Most suppliers don't stock a regular cab cover or incorrectly list it as the same as a quad cab. The first one I tried was a Dorman. Fit quad cab but listed for regular cab. This went in my 01 quad cab. The second one I got off Ebay and although it fit perfectly , the fabric was kind of a hybrid pattern somewhere between work truck stripe and SLT confetti. Last week I saw a new listing on Ebay and contacted the seller. They answered my questions correctly, so I bought number 3. It is a very close match to original (only real difference is cloth on the front where it drops behind your knees). Correct cutout for hinge. If you need a good seat bottom for your regular cab, look for seller "seatcoverreplacement" on Ebay. The cushion foam for these is stupid expensive. I compared the regular cab foam to my quad cab and found that with some trimming there is plenty of material in a quad cab foam bun to make a perfect seat bun for a regular cab. I only paid $39.50 for the quad cab foam

 

Good to know about the foam - I don't know about seat interchange between 12 & 24 valve Gen2s, but maybe that's another way to get a seat bun for the earlier 2nd Gens.

 

I've had good luck with Geno's garage and usautoseatcover.com in Texas.....

 

Geno's for foam and a vendor on Ebay for the stock cloth or leather.
Did the driver's side on my 1997 and it ran about $500 complete with install. Just like new from factory and well worth it.

 

Geno's has the bottom foam, and it's well worth it. I ordered one each for driver and passenger, then had my upholstery guy re-do my seats in forest green vinyl, with tuck and roll on the center sections of each seat. I love it!