Small block gas mileage DD magnum/LA ?

Honestly, IMO, I think it has to do with the fuel injection. The carb can run leaner if so set that way. The FI may be a tad richer, the cam slightly more aggressive making the whole package slightly thirstier? Perhaps the shocks itself has some small disadvantages as well.

Just like looking for HP, it can be a lot of little things adding up? Looking at the longevity aside of things, those Magnum engines are really something else! Cylinder bore wear is near nil on the ones I opened up with 80K, or even 150K.

From a performance stand point, as delivered, my 5.9 has been really good. An excellent driver on the street (even though it is converted to a carb) with very good power. I think it is a bit better than any 360 LA I have had in the past. No drag slips to support it. Just the butt dyno.