The first input shaft broke when it was in the original transmission engine package. Not entirely unexpected as the input shaft was a known weak point. The second (a300M alloy one) was a surprise to me as I only got about 15 miles before it broke. It shifted very hard and fast and I'm not sure if that had anything to do with it as I'm unfamiliar with performance automatic transmissions. We then did a $4,000 performance rebuild on another transmission and the first time I put horsepower to it I broke the last aermet100 alloy shaft that was available. I heard another opinion yesterday about the shaft alignment issue. So I've had two transmissions in the car now. How do I measure shaft alignment? Should I go back to the transmission that was part of my original engine transmission package. I was there once already with the 300M shaft. Should I go there again with a better tune for torque management? I'm back on the road again right now and driving it like a little old lady. The transmission seems ok except that the torque converter slips in and out of lock out with the slightest throttle variation. Personally I suspect torque management as the problem with the first 300M shaft failure. One of my transmission rebuild was due to a torque converter failure. I wish that I had been informed about the likely failure of that part. I would have installed a built torque converter with the transmission in the first place. I sure hope that anybody who follows me can benefit from my misfortune. I've spent close to $8,000 on my transmissions so far and all I wanted was to put my car on the dyno once with 15 lbs of boost to certify the horsepower, then run it throughout the 1/4 once to see what it would do. After that I wanted to feel the horsepower at 5-8 lbs occasionaly without beating on it and not worrying about breaking it. So far all I've got from my builders is "sorry about that, give me some more money and I'll fix it again".
