Put overdrive in your Classic vehicle. Conversions of automatic or manual transmissions.  We specialize in TREMEC T5's, TKO and T56 Magnums.


"Five/Six Speed Conversion Specialists"


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For help and guidance check out Tech Alley.
When you are ready to order review our ordering options in Customer Service then check out the Product Catalog. 

Have Questions? Send us an email with your details.

Note: If you already have a transmission, check out our transmission specs page to be sure the type you have will meet the torque your engine is providing.  


Tech Alley                                     "Where you find all the answers"


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 is only available as a used or rebuilt unit.  Service parts and upgrades are available such as carbon fiber synchro rings and steel forks.


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


Part Number
Torque Cap.
Gear Ratio Chart
1st 2nd 3rd 4th 5th Rev
Standard (260 0682R) 100 350 3.27 1.98 1.34 1.00 0.68 3.00
Standard II (TCET1376) 100 375 3.27 1.98 1.34 1.00 0.82 3.00
TKO (260 0708) 100 425 3.27 1.98 1.34 1.00 0.68 3.00
TKO II (TCET1377) 100 475 3.27 1.98 1.34 1.00 0.82 3.00


T-45    T-5    TKO    TR-3550    TR-3650

T-56    T-56 Magnum    S-197 Magnum


 Last edited: 2015-02-21 17:52