My series 3 has a 6 cylinder holden motor in it. the radiator looks like it is an original land rover item. The shroud on the radiator support panel has been extended with bolt on pieces of metal obviously during the conversion. The radiator is the type with the square header tank on top that extends further back over the top of the actual core, and has the round cap with no lugs on it.

My question is, how can you tell the difference between the 4 cylinder and 6 cylinder radiator (and in fact is there any difference?), I have seen both and they look like they are the same size. Are there any alternatives that will fit in with minimal modification and still suit the holden 6? I've seen the radiator from a holden used but required a lot of extra shrouding to be fitted. I think my system has a minor leak somewhere so I want to have some options that will make her cool a bit better.

Am I better sticking with the thermal fan or going back to the engine driven type?