how to tell if a zf5 speed transmission is fryer ?

Hi. I'm new to the forums here and looking for some insight. Looking at buying a 88 ford f450 with the 460 engine and zf5 trans. From my uncle. But the truck was towed to my uncles place forward on a wrecker and the tow truck driver didn't remove the driveshaft or axles for a 37 mile tow. I test drove the truck and it seemed a little noisey as most zf5 seem to be And Alittle loose shifting but seemed to work freely. Ive been told it will burn up the trans due to lack of oil flow. Is this going to become a problem in the future from the tow ???? Thanks for any info