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tucsonjwt · 07-24-2013, 08:12 AM

Visit the Gear Vendors website to see what they say about installing a gear vendor in an automatic. You may or may not have a fuel economy benefit from installing a gear vendor. I have a Gear Vendor in my 83 C20 454 with a granny 4 speed. GV advertises a 20% improvement in fuel economy, and that was true in my case (but only went from 9 mpg to 11 mpg city.) I think highway driving would show more improvement in fuel economy, but I never drive on the highway. Mostly automatics use the GV for increased power, especially when towing. Theoretically, you double the number of gears - somewhat like an 18 wheeler.

Two downsides of the GV are price and the need to modify the driveshaft (making it shorter, to accommodate the space taken up by the GV.) I think the GV units go for about $3000-$3500, plus installation cost. You need an adapter for the type of transmission you have - you can see these adapters advertised on ebay, and they seem to go for big $$$ and sell fast. There is a shop in Las Vegas which sells rebuilt units for less.

Also, you really don't use it much in city driving. I need to be going about 35 mph to engage the GV unit or it will just lug the engine.

07-24-2013, 08:12 AM	#7
tucsonjwt Registered User Join Date: Jul 2007 Location: Tucson, AZ Posts: 3,198	Re: Overdrive for a 454? Visit the Gear Vendors website to see what they say about installing a gear vendor in an automatic. You may or may not have a fuel economy benefit from installing a gear vendor. I have a Gear Vendor in my 83 C20 454 with a granny 4 speed. GV advertises a 20% improvement in fuel economy, and that was true in my case (but only went from 9 mpg to 11 mpg city.) I think highway driving would show more improvement in fuel economy, but I never drive on the highway. Mostly automatics use the GV for increased power, especially when towing. Theoretically, you double the number of gears - somewhat like an 18 wheeler. Two downsides of the GV are price and the need to modify the driveshaft (making it shorter, to accommodate the space taken up by the GV.) I think the GV units go for about $3000-$3500, plus installation cost. You need an adapter for the type of transmission you have - you can see these adapters advertised on ebay, and they seem to go for big $$$ and sell fast. There is a shop in Las Vegas which sells rebuilt units for less. Also, you really don't use it much in city driving. I need to be going about 35 mph to engage the GV unit or it will just lug the engine.