Chassis dyno with od trans

Just go back and do it in third.

x2 third gear is 1:1 in an OD manual tranny

If the dyno shop still has the files, they can probably just re-calculate and print out a new graph.

All a dyno really measures is torque. HP is calculated from torque. You can do that yourself if you have a torque curve. In fact, you can plot ALL 4 GEARS from one torque curve, by the same method.........just multiply by the gear ratio