[jocko]

You are correct, Longhorns started in 68 and there were no drw's. They were available as 8 lug C20 and C30 only (no Ks and no 10s) and had the 133" wheelbase rather than 127" - and, of course, were 6" longer in wheelbase and be length. Generally speaking, the 20 had an HO52 rear whereas the 30 had an HO72. Some may have come with D60 (20s or 30s) - but I'm not certain about that (*See update in post 6). Chevs were called Longhorns, GMCs were just "a truck with 133" wheelbase" - i.e. they didn't get the bedside "Longhorn" script even though identical to the 133" Chevs. Trim options were totally independent of Longhorn status, you could have a base or a CST or Cheyenne Super, didn't matter.