The honest answer to this i dont know. From my point of view been working in the motor trade and supplying parts for these they are a VW Transporter T25. The Volkswagen part numbering system for the year 1980-1990 transporter all start 251- (left hand drive) or 252- (right hand drive) Hence why i believe amongst the trade and VW Transporter Enthusiasts they are known as T25s.

But on the Continent they seem to be refered to as T3s im not sure where this stems from but if your in Germany, Belgium, Holland etc they are refered to as Volkswagen T3s. In the United states thay dont have this problem as they are known as Vanagons.

So to Put things simply if your own a Volkswagen Transporter 1980-1990 Model you can call it:

T25
TYPE 25
T3
(NOT TYPE 3)
VANAGON
WEDGE VAN
CHEESE VAN
BRICK VAN
BREAD VAN

They all equate to the same well loved VW Van

Please feel free to add your comments below together with nicknames etc.