Gear box oil cooler

Hi everyone i am trying to get a replacement gear box oil cooler for my 1989 3.5efi 4speed auto.
I have bin given a price of over £400.
I have spoken to a land rover specalist and he says the one on the car is not original but was not sure what it is from.
Does any body know were i can get one for less or a different cooler i can use.

I have a spare one in good condition.

Hi again iv just bin looking on the interweb and most of the coolers i have seen for the RRC are long ish and round. the one on mine is rectangle about 10inch by 4inch were these used or is it from something elce?