At about 2600 dollars (depending on model) the GEAR VENDORS is not the cheapest way for you to get overdrive but is by far the best. A Gear Vendors will handle more horsepower, deliver bigger performance gains, give you guaranteed trouble-free performance, and install easier than any other overdrive available. A GEAR VENDORS will handle 1200+ horsepower reliably and is under warranty even at the dragstrip. This is why you have seen GEAR VENDORS in 7 & 8 second ¼ mile cars in publications like Hot Rod and National Dragster. This is also why all GM Callaway Twin Turbo Corvettes with automatics came with a TH400 and GEAR VENDORS instead of the 700r4 which was the base Corvette trans.
You are also going to actually make more horsepower and enjoy overdrive cruising better with a GEAR VENDORS. For cruising you will have a dashswitch that allows both manual and automatic operation. With the switch in "auto" the vehicle will act just like it came from the factory with overdrive. The overdrive will kick in at 47mph or whatever the eprom is set for in our electronics and turn back off at slower speeds without attention of the driver. The ratio is .78 to 1 (see the final drive ratio chart below). This equates to 28% faster vehicle speed at the same rpm. Or, take your existing rear gear multiplied by .78 (ie 4.10 rear X 78 = 3.20). In this example a vehicle with a 4.10 has the same cruising rpm as it would with a 3.20 rear when the overdrive is engaged. The 3.42 rear gear will net a 2.67 final and yet have a 6.72 1st-over gear which is nearly as strong as a 4.56 rear car in 2nd (Awesome!). Plus with this step in overdrive you can still ran a 3,500 stall converter and cruise efficiently (see converter discussion in our "common questions" section) you're good with any torque converter you choose for performance. Your high stall converter will hook better from gear to gear with less drop when gear-splitting but also since the gears are closer there is not as much need for high stall and so stock converters perform to new levels of performance when Gear Vendors equipped.
Year One's '67 Chevelle Gear-Splitting is that feature which has made Gear Vendors so popular. Our 1:1.286 ratio brings the same close ratios found in a close ratio Muncie to your automatic. You will have a full 6 forward ratios and torque multiplication that will have even taller rear gears like 3.20 and 3.42 comparing to 4.10s. When you switch to manual on our dashswitch you control the overdrive. Pull into low, hit our button (on the shifter or the floor) this activates our Auto-Launch feature (a red LED light up on your dash), as you accelerate the car will rev in 1st and then shift automatically to 1st-overdrive which is a gear ratio right between 1st and 2nd and the green light appears indicating overdrive. You are now 28% farther down the track or road before you shift to 2nd. When you move your shift lever to 2nd turn us off. Then rev back up and hit the button for 2nd-over (this will also be a much higher torque multiplier than shifting to 3rd - see Drive Ratios). Then 3rd and 3rd over. You have never had this much performance, tire barking, and just plain fun driving your car. Even at just ½ throttle it performs, and at full throttle is just plain awesome. Look at the final drive ratios for each gear. Notice with your rear gear in 1st-overdrive how low you would have to go in a new rear gear to make 2nd gear have that much torque multiplication. A 3.55 rear Th350 will grab 1st-over like 4.5s in 2nd.
The equation for Horsepower is: Horsepower = Torque X RPMM/5252
Gear Splitting gives you more torque multiplication and higher rpm on shift = more HP!