Pete and KW also share the Pete Low leaf aka the KW ag400L. Pete air ride was actually a factory option on KW's back in the 70s paticularlly before the 8 bag came out. KW also had a 4 bag before the 8 bag that dated back to the 50s. You can recognize it by the air bags tilted at an angle. Yes the Pete air rode much better than the early ag100's. Somewhere in the 90's Kw redone the ag 100 with bigger air lines and faster valveing which made it much better. The ag 200 and ag 400 also ride better than the old ag 100. As far as the original question goes The front drive axle should be level with ground and the rear drive will be determined by the middle drive shaft length usually level or just slightly nose up.
Actually it could be as new as 99. That style was built as late as 1999 (maybe later) and was renamed the heritage series in 96 when the costellation style was released. As far as the big cam Cummins goes like everybody said Italeri just used the FLC kit with the WS cab. But that style of WS could very well have had that engine. Not to mention a glider kit could be powered by anything. Ws trucks like Petes and KWs didn't change styles for years at a time.
White or beige are both accurate for this kit. Revell's k100 is a "c" model between a 78 to 82 as the 8 bag air ride came out late 77 early 78 and KW went to the "e" model for 83. I've seen new Kw's with white engines as late as 1979. Yes it would be a white white if it was white.
All standard highway trucks have a track width on rear axles that make overall width between 95.5" and 96" it has nothing to do with frame and suspension widths. Like I said before steer axle track is generally a little narrower than rear axle track. Since you have to narrow the front axle on the AMT Freightliner any way a track slightly narrower than the rear axles will look correct maybe a scale 1 to 2 inches.