Chris, Thanks for your reply however, my questions were vehicle sp[ecific to Doug based on his engine mods....
eg,
What final drive gear ratio is in the 'Dually' ?
What trans do you have, auto or manual?
What do you normally tow and how far / often?
What MPG do you get with the eng mods you have performed?
Do you have any MPG numbers before vs after the mods?
Did the visor affect your MPG?
I'm looking for a suitable rig to tow a 27' house trailer to the race track and have a line on a low mileage, White ,'87 GMC, 454, Auto, Crew Cab, Dually (similar to yours) set up for 5th wheel and HD Platform hitch towing but, the owner's asking too much $$$.
Is yours, FOR SALE?
Thanks for you help
R. A. Watson
Ontario, Canada