Trutech Performance Transmission
go to last page

GM RWD Torque Converters

Starting 1980-up, GM used a 4-digit ID sticker located on the converter body to help identify it. Below is a guide to help decipher it's meaning

1st Digit (application trans)
  • B -- THM250C, THM350C
  • C -- 200C, 2004R, Pre-1984 1/2: 325-4L & 700r4
  • D -- 1984 1/2-up 700r4, 4L60, 4L60-E
2nd Digit (approx stall, depends on engine)
  • B -- 2025 rpm
  • C -- 2075 rpm
  • E -- 1654 rpm
  • F -- 1611 rpm
  • G -- 1397 rpm
  • H -- 1397 rpm
  • K -- 1211 rpm
  • L -- 1654 rpm
3rd Digit (Clutch Assembly)
  • 3 -- Poppet Valve
  • 7 -- Poppet Valve
  • 9 -- Poppet Valve
  • A -- Red (pre-96)
  • A -- Carbon (96-up)
  • B -- Static Open
  • G -- Carbon Fiber
  • H -- Red (pre-96)
  • H -- Carbon (96-97)
  • H -- Woven Graphite (98-up)
  • L -- Carbon Fiber
  • N -- Woven Graphite
  • P -- Woven Graphite
4th Digit (Body Mounting)
  • C -- 3 round lugs, gas engine
  • D -- 3 round lugs, diesel engine
  • E -- 6 round lugs, gas or diesel
  • F -- 3 square pads, gas or diesel
  • G -- 3 square pads, gas or diesel
If there is no ID tag, there might be a number or letter stamped between the dimples of the impeller on the converter body.
4th Digit (Body Mounting)
  • 4 -- 1211 stall
  • 5 -- Medium or high stall (depends on stator)
  • 6 -- 1397 stall
  • 7 -- 1654 stall
  • C -- 2075 stall
  • H -- 1397 stall
  • K -- 1211 stall
  • L -- 1654 stall

LS1 type 300mm Converter Codes

LS1 Style Converters:
  • 300MM Converters ~ 12" Diameter
  • 6.0 & 5.3 TMBX
  • 4.8 TLBX
  • 4.3 TLCX
  • 5.7 TMAX Camaro & Firebird LS1
2nd Letter is Stall:
  • M -- is low Stall 1500-1700
  • L -- is High Stall 1800-2000


Click To Email
Or Call 1-800-762-9846 Inside USA
Or 1-334-577-4400 Outside USA

Buy Now

Thank you for choosing Trutech Performance Transmission.