Here what I did on my day off-
I drove up a hill Loaded with a tandem axel oak decked 14' trailer with a New Holland 170 on it. I am running in OD with all the specs in my sig line below. I estimate the total load at 10k lbs.
you can see the effects of heat soak towards the top of the hill
I have to say I'm pleases with the transmission and stock injectors - these beasts were made to pull. The same hill unloaded I only pushed 25 psi. (40 loaded)

 

Nice video!

 

Still the 518?

 

Yep. Converter, deep pan, and some screw adjustments. I'm hoping to have it built up in the next year with all goerend internals.

 

Does pretty good.
Mine woulda water temp'd out because of the trans about halfway up the hill.