Getting a fan from the scrappy costs about £5 well at my local scrappy... But you don't know if it works, or how long it will work for.,.... Also finding a donor with one that fits may be an issue too... Most Production cars have platic molded fan housings shaped the same sixe ar their radiators, to remoce the fan and then fabricate some sort of housing can be an bigger job than you think....
I was asking for the depth as I've changed the location of my heater matrix and it now sits infront of the main radiator with a gap ob about 1.25 inched between the two radiators... Was thinking I could put a fan inbetween... I have a fatter, but smaller fan bolted on teh outside of the heater matrix blowing and the mechanical fan sucking... so if I manged to out an electric one inbetween I could do away with both of the others......