8000 Louisville single drives are reasonably light. Couldn't find the tare for my own as it was farm registered with the trailer but tracked down a spec sheet @ around 4T's.
My old Eastcoast K125 VT903, steel framed on torsion bars tares @ 8200kg, (scales confirmed) a similar speced truck with alloy rails I looked at first tared @ 8000kg.Both cabover Kenworths and Petes use alloy cabs with fibreglass roofs, engine tunnel and headlight panels. Petes do have alot more steel components in the cab, a goofy steel insert around the windscreens which are known to rust out badly. Where as the 74 on K100's being an all one piece roof and fibreglass windscreen cap have to deal with the ocassional loose fitting, leaky windscreens.I've noticed cabover Kenworths tend to use more alloy struts, baracketry in the entire cab construction (and plywood floors) than Peterbilt cabovers of the same era.One reason I guess why there are still so many of them still around. Worst part as far as corrosion in concered seems to be around the rear cab horse collar where the steel collar meets the alloy rear cab sheet.