True Auto Trucks had 3 wheels as per the pictures and the originals were JAP Petrol poweed Later one had achoice of Lister Diesels mostly HR twin Cylinders Some wee made in association with Crompton Parkinson , another Hawker Siddley group company and were Battery powered . Lister also made a four wheeled tug unit usualy HR 3 3 cylinder powered Lister eventually sold off the Auto Truck business and production moved away from Dursley How long it lasted I’m not sure But the last Dursley made ones were late 1970’s Ther is a Club for Autotrucks Listers had one as a works fire Engine which has been preserved Some had chassis designed to take skips of hot foundry waste and Swarf from Listers factory. Some had fixed dropside bodies some had low lowder type bodies for heavy stuff.there were even 3 wheeled tug units Spares should be aviable for the engines but Chassis parts may not be so plentiful The front Driving wheel had a pnematic tyre, most of the rear wheels were solid though pneematics were an option They were Film stars too making into the Italian Job and at least one James Bond movie !!

Thanks gents, some good starting info for me– thanks for your replies.