Engine temperature while towing

I had a 2001 Dodge with a 360ci & 4.10 gears. The temp gauge would also move higher somewhat under load. At the time I did some "google" search, 7-8 years ago. I found, don't know if its right or not, but the cooling in the 360 block had an area in the back that was close, or closer to the cylinder wall and had some type of pocket area in the back of the block that the coolant did not circulate as well as in other areas, thus under load would increase the temperature. I did add a bottle of "water wetter" as someone else recommended and it did help, and was only 10 dollars I think.
I don't know if the 318 block is the same as the 360, but it is from the same time frame.