Great, thanks for that link. That model# makes sense now, too. You are correct in what the truck started as. The 6004 in the model# stands for 60 = 133" and 04 = Wideside. The previous owner altered the truck to fit the much easier to locate bed for a 127" truck when it needed a replacement. You have a rare truck, something people will tell you doesn't exist. It's what GM did beginning with 1973, 1/2, 3/4, and 1t pickups all using same wheelbase... and bed. Your truck is ahead of it's time!
