1986-1995 Ford Mustang 5.0L Tremec 3550 Transmission World Class T-5 302 T5Z TKO

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