Gt18 hydro drive oil cooler duct ??

Hey all just got signed up to the community have been visiting this site for a long time and love it !! Any way just got a 78 gt18 hydrodrive this summer to add to the fleet been working on fixing it up but I'm missing the oil cooling duct on the side of the tractor that goes over half of the engine and over the hydro oil cooler ? Does any one out there have one for sale or have a tractor with one that could get me diementions so I could make a close to original one for my tractor any help would be great thanks