Have a look at what engine is in it - there are are not many Diesel engine manufacturers and this will give you some clues. (Common in Sweden = Ford, Lister-Petter, Perkins, MAN, Deutz) On many of them the number is hard to read if it's been overpainted so you'll need to look carefully and use a wire brush to find/read it. Usually they are on the bell housing (kopplingen) or stamped on the cylinder block. Sometimes you will find model details on a plate on the firewall (the metal wall between driver and engine) - usually on the engine side.
