Installed at last. I have a D300 flatbed with a 383 and 4 speed. Back in 2003 when I first owned this truck, I had a Spicer 3 speed aux. trans installed. I sold the truck in 2004 and bought it for a second time last year. The truck had a serious vibration, which I felt came from the Spicer. Anyway, I had a chance to get a GearVendor overdrive that I had owned at one time from a Dodge Cummins 5 speed. The GV was tired and needed a rebuild. Bottom line, the rebuilt GV now installed In my D300 along with all new drive shafts, carrier bearing, etc. LOVE IT. I have essentially 7 forward speeds 1 PLUS 2,od 2, 3,od3 , 4, od4). Splitting the gears is so easy---just move the button on the gear shift lever. The Dodge has a 4:10 rear and now 65mpn is about 2300 rpms with 4od. AND vibration is gone!