I always cruise at about 70-75 With the 3.0 LWB truck.. It definetly has much more to it with the reman'd engine, but I can squeeze 21mpg out at that speed and that's about the best I can get. My 4 cyl shorty has touched 100 on occasion (downhill) but the fastest flat out I can actually cruise at is about 85, and that gets me a rewarding 15mpg (before adding 33" tires)

1999 Mitsu Montero - Crappy Weather
1992 Isuzu Pickup - Zombie Apocalypse
2008 Saturn Sky Redline - Nice Weather