Torque Converter identification


Active Member
Aug 7, 2017
Hello all!

I’m installing my built C4 into my 90 GT and I’m looking to identify the torque converter that came with it.

I bought this transmission from a long time family friend who had it built but then ended up going a different direction.

I have all the paperwork for everything except the torque converter. I have no idea what it is, or what the stall is. All it has on it is one number stamped on the side:


any ideas?



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Active Member
Jul 12, 2018
Hi Justin,
The old school talk of the “torque converter diameter being smaller meant a higher stall speed” holds some weight, but is not always true. Can you pls.wrap a soft tape around and post the circumference?
Mfg’s usually stick to their colors, and external design sometimes differs, see attached.
A stiffened 89’-90’ GT (W/Driver) at 3,300lbs with a 350-370BHP 302/306 running a built C4 with a 1:1 top gear ratio winds roughly 2,700RPM’s at 60 MPH with 3.73’ gears. With all the above, the 286 Deg. Adv duration of an X-303 Cam, it’s 2,300-6,200 RPM range, with street/strip intent considered, I’m guessing a 2,800-3,000 RPM stall speed selection. I’d expect it to be near 500RPM’s below the advertised stall due to the car’s weight.
There is the option of sending it out and having it function tested where things like stall speed, flash rpm, lockup (where applicable) values will be given, as it’s performance testing..
Or, just replace the Trans front & rear seal, vacuum modulator and install it & see where the dust settles.
Converters range from 150$ to 1,500$+, average decent street/strip 350$.
Your C4 is a 72’-73’?...
1971-1980 C4 TransmissionW0.839 inch with 26 splines at the torque converter and 24 splines at the clutch hubD0-D7 Casting NumberP R N D 2 1
Helpful link(s):

P.S. Reference picture for ID is from TCS, Inc.


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