SimonRS2K:
Unipower
Correct 
HERCULES Econofreights 6x6 Unipower ballasted tractor
It weighs 43 tonne without a trailer, it is 10 foot wide, the cab was fabricated using the shell of a Volvo Globetrotter, and extended to allow 3 bunks for the crew and a kitchen area…
and yes, it has a ■■■■■■■ engine 
I never drove this on the road 
, and only moved around the yard a few times…