What is the best pre-emissions engine/truck combo?

Mack E9 V8 in a Superliner! On my bucket list...

 

Trying to understand what is really "Pre-Emission". But anyway to de-bunk this comment, I have a 07 Cat C-15 with over 900,000 and averaging 6.7 -7.0 mpg with no performace upgrades. Only thing is the truck had super singles on when I bought it with 700,000 miles on it and my mpg was 6.9 -7.3

 

Cummins N14,,great engine I got 1,250,000 miles on mine before I sold it , the guy that bought it has added more than 600,000 trouble free miles,,wish I kept it ..I Put new pistons in it at 700,000, had 2 cylinders with a stuck oil ring so replaced them all, new injectors at 980,000 miles..

 

6nz cat and 12.7 detroit.

 

I am rather partial to the factory rebuilt pre-egr 12.7 Series 60 in my 2013 Freightliner as far as a engine/truck combo is concerned. Would be equally as satisfied with a N-14 in this truck. Have had, and still have, great results from both brands and models of these engines.

 

The pictures with 8.7-8.9 mpg, what speed were you in.

 

I've got a '98 T800 with a 1LW 3406E rebuilt and retuned to 550, it was 475 from the factory, oil cooler let go at 678000 miles, ended up inframing it then, pulls like a dream, 102000 lbs hauling cattle it will do 5.5 - 6 depending on how I drive it and the head wind, Can't go wrong with an E block or C15 powered KW in my mind

 

Of course it varied, as I run a lot of two lane along with interstate, but out on the 4 lane I usually run 63-65 mph with occasional bumps higher for short periods when I need to break free from a traffic bunch up. The engine seems to do it's best work at 1475-1500 RPM.

 

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I have a 1999 379 305 inch wb with a 525 celect plus and 18 speed pulling a skate. I get 6 to 6.9 running the mountain west 65 to 70 mph. I've had a 94 3406e , a 2002 6nz (both 550's) and this N14. I love the N14, pulls just as well as the cat but better mpg. My ifta average runs at 6.45 usually.