[eschaider]

Horsepower does not break rear ends or, for that matter, anything else in the driveline. Torque breaks everything. If you take a relatively small 500 HP Cummings diesel, with a governed engine speed somewhere around 1800 or 1900 rpm, and hook it up to a TKO-600, you might believe the TKO had a chance of surviving until you discover the engine has over a thousand foot/lbs of torque just off idle!

Guess what happens to the TKO (or TKX) if it is hooked up to a load and asked to pull it? If you haven't guessed yet, the diesel reduces the transmission to a basket of badly broken part segments — and this happens at around 250 HP or so. It is clearly not the HP that is breaking parts; it is torque!

Most aftermarket parts providers have no idea about the safe power (torque) transmission levels of the transmissions that they sell every day because they have no way to measure it and do not, so they SWAG (Scientific, Wild, Ass, Guess) it. Because HP gets all the attention, the suitability or right-sizing reference quickly goes to HP, and no one gives a second thought to torque capacity, but they should — and so should you if you are building one of these cars.

HP will get you bragging rights. Torque will destroy drivetrain parts. If you are writing the checks for the repairs, it is to your advantage to understand the difference.