Typical increase in MPG when swapping to OD?

[ponjohn]

Hi All-

Have not been around, sold the 85 dually a few years ago. I am looking at a 90 Burb, TBI 454, 2wd,4.10 supposed to be in real nice shape for the age.

It needs a trans, my intent will be to install either a 700r4 or 4l80e ( I have both).

Sooooo.....anybody go this route and document the increase in fuel economy?

( I put this in here because there is more traffic)

TIA-
John