Sounds like it's time to get the tape measure out and see what's in your truck or find someone with a 5756B that's sitting on the floor...
You need to confirm the Pilot bearing size, shaft size, spline count, length of the input shaft and trans to bell housing bolt pattern. I don't see the 3053A as ever being in a GM truck from the factory, so my parts books are no help.
The Medium Duty trucks could have a 11", 12" or 13" clutch.
Does your 427 have a SAE transmission adaptor ring for a SAE bellhousing or does it have a GM bellhousing?
Mike B
