Yes it is true.The V8's in these vans do get the same or better gas mileage as the 4.3's.The thing is when we built 383's in the past,we never even considered gas mileage.On the other hand I know a guy in Calli with a 355 in his van and it uses a early Edelbrock injection system.This is going on three yrs since built.He tows his sand rail on a open trailer and soft peddling threw the mountains out there gets 22 mpg.When he beats on the van gets still 18 mpg.Now it goes beyond just what I have said about the build.The van has a really well developed tune on it too with port and polish etc.It is owned and built by a master Mercedes tech who really knows what he is doing.

I need to decide if the difference in gas mileage between a 350 vs a 383 is worth it to me.Really what would the difference be??.