Frankydobo:
My 74 edition arrived today thanks to E-bay and in great condition too so that’s the set complete, at least I think so my original 67 book is a reprint of the 66 first published book, I wonder if there were any changes. Mmm this has got me thinking now! Cheers Franky.
Thursday,27th April,2017.
The Observer’s Book Of Commercial Vehicles.
1966 Edition
1967 Reprint of the 1966 Edition.
The 1966 edition of this book has a photograph of an AEC Mammoth Major Eight MkV 691/760,Park Royal-Cabbed,Tanker-Bodied,8x2 or 8x4 Lorry in the AEC section.
The 1967 reprint edition,however,has a photograph of an AEC Mammoth Major Eight 691/760 Ergomatic,GKN Sankey Ergomatic-Cabbed,Tanker-Bodied,8x2 or 8x4 Lorry in the AEC section.
As far as I can see this is the only difference between these two editions.Why did the publisher,Frederick Warne & Company Ltd,change the photographs? There was a production overlap of AEC Mk5 and AEC Ergomatic models in the 1965-1966 period:MkV models were produced at the same time as the Ergomatic models,but by 1967 the Ergomatic range,with the exception of the MkV Dumptruck,had fully replaced the MkV models - so the 1967 reprint edition of this book has an AEC Mammoth Major Eight Ergomatic lorry…not as impressive and as attractive as an AEC Mammoth Major Eight MkV Park Royal! 
There is also The New Observer’s Book Of Trucks,Nick Baldwin,Warne,1986,Paperback (and Hardback?),the front cover photograph is of an attractive
woman lorry driver driving a red Kenworth T600A Aardvark,Conventional-Normal Control-Bonneted,Sleeper-Cabbed,Aerodynamic-Streamlined,6x4,
Boxvan-Bodied,Articulated Long Distance Heavy Duty Freight Trunking Motortruck-Lorry.
An hardback edition of this book was published in 1993 by Bloomsbury Books,and was just a re-print of the original 1986 edition.
This is a re-formatted book based on the original Observer’s Book Of Commercial Vehicles.I prefer the original editions as they have more details
and were in alphabetical order of marques,which are easier to look up,plus most of these editions also cover motorcoaches and buses.
VALKYRIE