I doubt that there is anything wrong with your trans. Getting really hot towing up a steep grade is normal.

 

If it got that hot, I'd get a complete fluid exchange to be safe.

 

I am planning on installing a remote oil filter when I install my new tranny, just going to use a cheap mount for a PH8a filter.. Should I put it in the out line or in line. If it don't matter. but Which line is the line to the cooler too. I can't just disconnect it and see which direction it is going. Don't have new tranny yet.