Towing with a small block

[THI]

I know this is an old thread, but I thought I would add my experience. I had a 1988 V20 Suburban with a 350 TBI/TH400/4.10 combo - got 12 MPG empty or towing. My next Suburban was a 1992 K2500 with 454 TBI/4L80E/3.73 combo - got 16 MPG empty on the highway and 13 MPG towing about 6,000# in Drive. My 1996 K2500 Suburban with the 454 Vortec/4L80E/3.73 would get 15 MPH empty and 13 MPG towing 6,000#. Bump that up to 10,000# towing and it would get 11 MPG (and you knew you had 10,000# on the hitch! My old 1988 really did not like to tow more than 6,000# with the 350 and I always wanted to replace it with a 454 from the day I bought it!