try unplugging the trans connector at the back of the trans it will hydraulically go to third gear and try what you were doing before and if the converter still locks its not electrical problem but a problem with the trans or tc :thumb:
you still have to remember there is a limit to these cranks just like any other crank even if the common problem is fixed it will still break at some point, especially when these "failures" happened on pulling trucks they are ran HARD with plenty of driveline shock.
It wouldn't hurt to pick up a bottle of ultra torque the small packets that come with the studs doesn't get very far when you put a good amount on
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I think your c1 clutches are stacked wrong so that on the lift with no resistance it will hold but on the ground there is enough to slip the clutches. I think they might be upside down or in an improper sequence or your c1 piston could be defective as said above
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Last I heard he "built" a allison for a kid with "high performance Borg Warner clutches" aka stock clutches with a shift kit
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