Paul
You need to speak to Michael Eyre of the Crossley Register about this as he has done much work looking into the FWD types. However, the picture is a bit confused.
In the CR Newsletter #39 (Spring 1998) Michael says:
Production variants were identified in Crossley's usual manner - there were Types 1, 2 and 3 for the truck and Types 1 and 2 for the tractor. The cabs on the later FWDs were built by Mulliners Ltd of Tyseley, Birmingham; most were of a simple square-shaped design, being easy to repair in the field but those on the later Type 2 tractors were of a rounded style and they were usually kept in England. Other variations were engine power rating of either 91 or 96hp (often referred to as 100hp) - the latter for fire engines.
However, in his book "Crossley" (published 2002; co-authored by Chris Heaps and Alan Townsin) it says:
There were Type 2 and 3 of the truck and Type 1 and 2 of the tractor. The principal difference was engine power - either 90 (Type 2 truck) or 96hp (the rest)... Later engines were further uprated to deliver a full 100hp, some being fitted with aluminium crankcases instead of iron ones. The transmission details also differed - on the Type 3 trucks and all the tractors (but not the crash tenders) the two-speed auxiliary gearbox was modified so that four wheel drive was engaged only in low gear. This made the vehicle more economical on normal roads and reducing wear on the tyres... The final variation of the Type 2 tractor and later trucks was the addition of accessories, such as a tyre inflation pump, driven off the gearbox, and extra electrical equipment.
The article lists contact V4326 as being for 695 truck Type 1 units in 1941; whereas the book says order 294/V4326 was an amalgam of six orders between 1939 and 1941 totalling 2,807 units (552 being airfield crash tenders).
As you can see, some contradictory information; possibly as a result of fresh information after writing the first article. It's not clear, for example, what happened to the Type 1 trucks; or whether the Type related to the cab design or not. As I said, best speak to Michael about what he knows. He also maintains a list of survivors.