Overdrive Conversion Fit For A Classic Truck - Five-Speed Fever! - Tech

Fuel economy and gas mileage are two terms that are impossible for truck enthusiasts to ignore these days. With the current trends in the price of oil, those of us driving gas guzzling or otherwise unfriendly fuel, consumers are going to get hit the hardest. There are numerous ways to increase the fuel efficiency of your truck, from updating that old Quadrajet to a modern EFI system, to changing the gears in your rearend. But one of the easiest and perhaps cheapest ways to go is to install an overdrive transmission. For those of you running a Muncie or similar manual trans behind a small-block Chevy, dropping in an overdrive manual trans such as a T5 or a Tremec TKO can't get any easier. And while a brand-new overdrive five- or six-speed gearbox may not be the cheapest way to reduce engine speed and gain fuel efficiency, there are junkyards filled with a great alternative, the T5.

Originally manufactured by Borg-Warner Automotive, the T5 transmission originally appeared in the early 1980s. These early T5s are classified as non-World Class (NWC) and are rated for slightly less power than their later World Class (WC) counterparts, which appeared by the end of the decade in the Mustang, Camaro, Firebird, and even some Jeep lines. Since it is the only American-made transmission to span more than 20 years, there is now a good supply of T5 transmissions, both WC and non-WC, in salvage yards across the country. Given their relative abundance, they have become a very popular option within the hot rod crowd when it comes to an economic overdrive manual trans. With five fully synchronized forward gears, overdrive, an internal shift-rail mechanism, and the ability to handle more than 300 lb-ft of torque, the T5 is also one of the most versatile manual transmissions available. During the past ten years or so, supported by a strong aftermarket industry supplying adapters to a vast number of vintage engines, the T5 has continued to increase in popularity. Add to that the compact size and lightweight of the T5 and you have a transmission that seems almost tailored for use in a classic truck.

One of the problems with the later WC T5s is shifter placement. While the Muncie, T10, and other vintage boxes placed the shifter relatively close to the bellhousing, the WC T5 places the shifter way back on the tailshaft, too far back for most early trucks. This often causes interference with stock bench seats, among other things. The S-10 truck T5, however, has the shifter in a more appropriate location, about 10 inches closer to the bellhousing. While not as strong as the WC trans, the NWC S-10 transmission would be fine in a mild truck with, say, a Flathead or inline-six. But with the T5 trans, you can have your cake and eat it too. Because the T5 transmission has been produced in such large quantities and in such a wide variety of models, there are a few different variations of the original design and, luckily for us, the parts needed to relocate the shifter position are interchangeable. This is great news, but requires either finding the correct two transmissions or a good WC trans and a few parts it takes to make the conversion possible.