Deffinitly want the 3607...T or TR.

I prefer the TR (red needle)...less harsh at night, but it's really personal preference.

 

Max egt is personal choice....I ve run gas engine up to 1700+ one as high as 1900 by accident with no damage. Those are brief amounts of time thou. Pulling a hill I back out at 1375-1400. I do that cause I know from experience that my engine doesn t mind 1350 all day long. I was towing 28k....

On a hill you dont want to back out.....its harder to get rolling again...etc...know your happy rom range....if 5 th gear gets dragged down alittle egts will rise because boost is falling cause rpm is slowly dropping....so grabbing fourth gear raises the rpm, brings boost back up and moves more air...so typically you can go to fourth gear, drop egts 100-200 and only lose 5-8 mph....

I run at 70-76 ussually in 5th, I down shift to fourth at 68-70 mph (3.54 gears) If I shift at 70 on a hill, my mph drops to 68 by the time it takes to shift, but then the rpm is at 2600 or so in fourth....air low through the engine goes up, and boost ussually goes up.

I ve heard that cummins tested engines for 24 hrs at 1350 ....but who knows where it was measured....etc.