gingerfold:
Just been having a catch-up read of the latest posts as I couldn’t join the debate last evening as I had a central heating breakdown at home to try and sort out.Without digressing too much from the main theme of the discussion, i.e. the AEC V8, as we keep getting the Detroit Diesel 8v71 mentioned then it begs the question why did it become an option in certain Scammell Crusader models? It might have had some special types applications in the UK before the Crusader, but in standard UK truck specifications it was an unknown quantity.
The answer as to why the Detroit 8v71 was used in military 6x4 Crusaders is because the MoD specified it. Obviously Scammell had a long standing relationship as a supplier to the MoD, and its predecessor The War Office, but all military vehicle contracts and vehicle specifications are agreed by the manufacturer and the MoD procurement departments. Some military vehicles are very similar to civilian vehicles, for example AEC Mammoth Major 6x4 refuellers for the RAF, others are far more specialised. And different branches of the armed forces have their own special requirements.
Back in the mid-1960s, when the Crusader range was first planned, as a military vehicle in its first inception, the Cold War was at its height and all the military strategists believed that non-nuclear land warfare between NATO (spearheaded by the US Army) and the USSR would be fought on the plains of North Eastern Europe. Deployment of tanks and other military hardware would need to be done quickly on an established road network and there would be a pooling of logistical resources, if necessary, between the NATO allies. As the Detroit Diesel engines were common in US military vehicles and other motorised equipment then by having British and NATO vehicles with the same engine types then it was better for battlefield maintenance and repair facilities. The scenario of US maintenance units repairing Scammell Crusaders would have been considered. The Detroit Diesel engines had their origin in the early 1940s, this specialised division being set up by General Motors to supply the US military.
I am fortunate in that my brother in law was a career civil servant and worked in the MoD for 43 years until retirement at a very senior level. He was stationed at NATO headquarters in Brussels from 1973 until 1975 and such was his seniority that he took part in “war games” with senior military top brass at various times in the UK, Europe, and the USA.
No doubt the above information will be dis-regarded by one or two, but my research has been backed up by my brother in law who has provided the military scenarios outlined above. So, that is the reason that Scammell used the Detroit Diesel 8v71, and the ■■■■■■■ V8-903 was also listed, but whether any were built with that option is not known.
Which leaves the question that most if not all military Crusaders used the …Rolls Royce Eagle not the 8v71 ?. 
Also bearing in mind that the cold war and NATO operations were no different through the 1970’s as they were through the 1960’s.Also bearing in mind that the US forces had no problem working with Brit forces using the Rolls petrol engined Centurions in Korea and Europe to the point where they actually preferred the Centurion to their own tanks.On that note NATO obviously had a massive range of different trucks varying from Brit Bedfords.To the Antar which of course had the cut down diesel V8 version of the V12 petrol Meteor in the Centurion both of which obviously being two totally different pieces of kit until the Challenger and Commander appeared using the Rolls CV12 although still two totally incompatible different ratings of the same engine.All also being totally different to anything in the US inventory like the US M 123 and 125 themselves using both Le Roi petrol and ■■■■■■■ V8 diesels together.While ironically the 8 v 71 seems to have had a relatively limited role in US forces vehicles the main one being self propelled artillery in 8v71T form.In which case I’d doubt that Brit forces vehicles often if ever needed to be worked on in US field workshops or vice versa at that time.
While the Brits seemed to have had no problem dealing with a mixture of different engines varying from Continental radial petrol to Detroit diesels in their Shermans during WW2 the different fuel supplies being the main issue in that case not parts etc as I heard it.Which then leaves the question of the 8v92 replacing the Rolls CV12 and then CAT replacing the 8v92 in the HET with the US using a gas turbine powered tank v the Brit Challenger 2 still using the CV12 and ze Germans using the MTU in the Leopard and their own SLT Deutz powered transporter.IE a total mish mash which makes any idea of rationalisation in NATO to date erroneous and moot.
So I’d guess that any NATO link with the 8 v 71 Crusader is a red herring and the choice was simply that the 8v71 was the better V8 diesel than the AEC ( or the ■■■■■■■ 903 ) that mainly if not all about civilian orders.
Which then still leaves the question of the how and why of the situation of Scammell emerging unscathed form the AEC V8 debacle by way of the choice of the 8v71.That choice having nothing to do with NATO or the military but obviously someone at Scammell calling a spade a spade in the case of the AEC V8 and Stokes agreeing with them. 