the first movin' on truck, yes it's hauling a B.J. and the Bear trailer those are all different, the guy who owns the movin' on truck in the first photo also owns a B.J. and the truck & trailer the three original were 2 1974 Kenworth W900A Vit's & a 1972 Kenworth W900A VIT each photo is of each truck still existing today

Looks like the trailer towed by B.J. McKay's(Greg Evigan's) late-70's K-100 Aerodyne:
http://imcdb.org/vehicle_42863-Kenworth-K-100-Aerodyne.html

one more photo that trucker missed that was a photo from "the big switch"

the original 1972 Kenworth W-900A VIT, first truck ever bought for the series

the other original 1974 Kenworth W-900A VIT's

Here are the photo's I promised
http://imcdb.org/vehicle_42128-Kenworth-W-900-A-1974.html

one of the original 1974 Kenworht W-900A Vit's