Hey guys.. got a problem with my trans.. I bought it off of a member of another board..It was supposedly built to handle like 600hp and was behind a 468ci BBC.. I put it behind my 406 SBC, pushing 400hp..

I installed the trans and got everything hooked up properly.. The guy included a driveshaft that was already cut to length for our cars.. but when I went to install the driveshaft, it didnt quite clear the pinion yoke.. I had to remove the two caps off the u-joint and turn it a certain way to get it to go in.. So i got it in.. Drive it a bit.. topped off the fluid,etc..

Now I started getting a rattling from the tranny, sounds like it is in the rear of the tranny.. I have a hole in my floor, so I can hear it pretty good. It happens in 2nd,3rd and 4th is the worst.. Mostly under anything more than part-throttle..

I was also getting a bad vibration.. So i got under the car and measured the clearance of the driveshaft( also had new u-joints installed ) and it turns out it was a little too long.. I only had 3/8" clearance on the trans slip yoke.. So I re-measured it so I would have 1" clear.. took it to a driveshaft guy, he cut and balanced the driveshaft.. The vibration was definitly from the shaft.. It was way out of balance..

Anyway, I get the driveshaft back in, take it for a test drive..Still got the rattling in all gears, well not 1st..

I also had another catastrophe. When I re-installed the driveshaft, I didnt use the c-clips that locate it in the pinion yoke. I didnt have them, so i didnt know I needed them.. Well, the u-joint cups flew off while i was driving, the driveshaft spun about a 1/4 turn in the pinion yoke and wedged itself ****-eyed, the whole car shook violently..I got it to a stop, pulled the driveshaft and had it towed home..

anyway, I was just wondering what the rattling could have possibly been? I have another 700r4 I am going to use, but I wanted to know what went wrong..

tia