Overheating transmission
 

Hello Everyone, I am new to the forum and would appreciate some advise. I have a 1992, F-350, 4x4, 7.3L diesel with EOD transmission. I have been plowing parking lots and the transmission is overheating. I have been told that it needs to be rebuilt for a sum of money I do not have. I installed an external transmission cooler. changed the fluids from the base and the converter, installed new filter. I was plowing in high range and have switched to low range and have been able to nurse the truck a little. I am removing 2 air horns from in front of the radiator for better air flow. I am thinking of trying synthetic fluid and maybe another transmission cooler to help . Well having all these thoughts do you think I may be wasting time and money? Thanks for any input you may have.
Luke