TECH GUIDE: Tremec TR 3550

The TR-3550 five-speed overdrive transmission was developed to provide great torque capacity and is ideal for specialty sports cars equipped with high torque engines.

The 3550 was both a product and a product line.
The product line encompassed the 3550 and TKO models. Each model had two versions,  one being a 0.68 overdrive and the other being a 0.8 overdrive.
The difference between the two models was in the gear ratios and the input shaft spline count,. as explained below.

In 2004 the 3550 and TKO were replaced by the TKO-500/600 product line.
Today the 3550 and TKO are only available as a used or rebuilt unit.
Service parts and upgrades are available such as carbon fiber synchro rings and steel forks.

4.2.7

Features & Benefits:

• Five forward speeds with 5th gear overdrive provides extended ratio coverage, lowering engine RPM’s and improving fuel economy. (Available in .68 or .82 overdrive ratio)
• Tapered roller bearings on input, output and counter shafts increase torque capacity.
• Massive 83 mm center distance from mainshaft to countershaft allows for the largest most durable gear sizes.
• Specially designed aluminum die cast housings provides optimum strength-to-weight ratio.
• Steel input shaft retainer enhances durability.
• TKO models are offered with upgraded steel on select gearing, delivering maximum torque capacity.
• Internal multi-rail shift linkage system provides robust, positive shifting.
• Fifth speed synchronizer located on countershaft reduces gear rattle and shift effort.
• 10 Spline input shaft (3550) or 26 spline (TKO)
• Multiple shift lever locations available:
  • Rear – standard on all TR-3550 transmissions – ideal for Mustang applications
  • Mid-shift location – ideal for pick-up truck retrofits
  • Front-shift location – allows retrofits of custom-made cars and other Hot-Rod applications