Just a word of caution:
transmission coolers are NOT the same as
oil coolers... The channels are different sizes, with transmission coolers having smaller channels, as the transmission fluid is thinner, less viscous. I would advise against using a transmission cooler for engine oil. Check out the vendor sites for companies who sell such things -- you will see that they market different coolers for the two applications.
Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII