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Core Shifter Base: Tremec TKO / TR3550 aftermarket

  • $ 15900


Core shifter base for custom conversions:

  • Only fits Tremec TKO 5 speed aftermarket transmission (sometimes referred to as TR3550)
    • Does NOT FIT any other model - see my other listings for Magnum etc
  • Replace the Tremec-supplied base with a higher fulcrum to reduce throw
    • Tremec's fulcrum height is only 1.9"; follow the list below for substantial improvement!
  • Mounts at tail location on a rectangular 6-bolt pattern that is ~ 3.02" wide x 5.50" long; stub pivot ball center is ~0.625" below the flange
    • NOTE: This listing is for the "newer" TKO shifter bolt pattern that is the same width front-to-rear
    • If you have the old bolt pattern that is narrower at front, please email me

A Hurst stick is required (sold separately). Other brands and homemade sticks are discouraged. Stick mount has 3/8"-24 threaded holes spaced 7/8" apart on center + mating serrations for a Hurst stick on one face. Due to larger mounting threads (3/8"-24), sticks that use 8mm mounting bolts (most OE, "non-TKO" Lokar, others) will not work. Lokar TKO sticks can be mounted but only to the smooth side of the stub. To select the proper parts:

  • Wait until new transmission is installed to buy shifter parts
    • Remove existing shifter base if present
    • Sit in vehicle, in driving position, with all interior trim (dash, console, etc) in place
  • Define desired knob location in space (neutral position):
    • Measure height from base flange to desired knob location = overall height
    • Measure side & rear offsets from receptacle bore to desired knob location
    • See this diagram for clarification
  • Study the Hurst stick page for shapes that meet your needs
    • Allow 3-6" for stick mount height
    • Choose a stick and see what fulcrum heights are compatible with it (see chart)
    • Check overall height (see chart: stick height + mount height = overall height)
  • Confirm chosen combination achieves desired knob location and that fulcrum height works with stick length selected
    • Consider various stick & stub combinations to optimize
    • Note long sticks on angled mounts will strongly offset knob to left (can be 5-6"+)
    • Note OE dust boot is short and exposes stick mount which helps in tight situations
    • Options E & F require a Hurst stick directly mounted on side w/ serrations

Stub fulcrum height options (critical to optimizing leverage for short throw):

Option For stick length stick mount height stick mount angle boot type upcharge
A 8" 3.7 vertical Billet Plus default
B 10" 4.2 vertical Billet Plus +$10
C 10"+ 5.2 vertical OE (short) +$20
D 12"+ 6.0 angled 14 deg left OE (short) +$30
G 6" 4.2 angled 11 deg left OE (short) +$10
  • Stick length = point-to-point distance from mount hole to knob thread
  • Stick mount height = distance from base flange to stick bolt hole (affects knob height)
  • Fulcrum height = distance from lower ball to fulcrum pin; varies by option, not published
    • Warning: Follow stick length guide to avoid excess effort & component failure

Kit includes mounting hardware, dust cover boot, and instructions. The base is built by Core Shifters using proven Hurst Billet Plus components inside a custom housing (not produced by Hurst, but made in USA). It does not have stops and does not need them; all modern internal rail trans have internal stops. This kit has many superior features & components, integrated into a unique, exclusive assembly:

  • Forged heat-treated billet steel gear selector stub
  • Hardened steel cross-pin & stainless steel fulcrum pivot ring
  • Self-centering cross-gate bias springs with heat treated spring seats
  • Glass-reinforced polyamide fulcrum socket with steel wear clips
  • Rubber oil control seal with steel retaining ring
  • 6061-T6 extruded aluminum housing with Spirolox steel support ring
  • Zinc-plated laser-cut steel base-plate & cover
  • Vibration-resistant serrated flange head steel retaining bolts
  • Rubber dust cover boot (style varies)
  • High quality & outstanding value!

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