I am looking at a 1990 3500 Dually 4x4 700r4 4:10 gears. What are realistic fuel mileage expectations? Will 14 on the road empty at 70mph be a far stretch or are we looking in the single digits?

Probably 6-9, those 454's like to eat gas. ;o

My 85 454 2WD gets about 10.... That's the reason I can't get rid of it!

MAS
85 GMC Suburban 2500

my 91 R2500 with 454 gets around 10-12mpg on the highway with 170K miles, 10 in town. you may get about the same or better if that 700r4 had Overdrive, otherwise closer to 10 is realistic. Mine has the 4L80E tranny with O/D so it does decent on the highway... feels liek it floats along nicely :D

I know an 88 gmc 3/4 tbi 454, 400, 4.11 4x2 that got 14mpg with a 4'x15' culvert in the bed on a 200 mile trip, and 16 on the way back. My brother's 98 k2500 with port injected 454 and 4l80 gets 12 empty and tuned up and 10 if it isn't. It got 8 from Chicago back to Kansas city with 2 early 70's buicks on the trailer behind him.

Is this`90 a dual or single wheel?Does it actually have an 700r4?I didn`t think they came with that trans from factory.Should be a 4L80E.Is this the new-style`90 or old-style?You didn`t mention cab type.I know the older style didn`t get o/d until`91(if it`s a 3+3).

Is this`90 a dual or single wheel?Does it actually have an 700r4?I didn`t think they came with that trans from factory.Should be a 4L80E.Is this the new-style`90 or old-style?You didn`t mention cab type.I know the older style didn`t get o/d until`91(if it`s a 3+3).Hey wait,I just saw this is the Suburban section,now I`m:confused:.