ok here is the story.... i got a blazer a few months ago. and in less than a month it will be my DD.. i put a muffler on it a week or so ago and it was kindof close to the transfer case. but i figured it would clear so i went ahead and put it on (using clamps so i can move it).. the first time i drove it it was fine sounded good ran good, everything. i parked it and came out the next day and started it,..................... sounded like something was hitting the fan. looked but nothing was there, the noise stopped after a couple of seconds so i was confused to say the least. then i drove it around for a minute and it started making a chattering noise that sounded like it was coming from where the muffler was, so in the back of my mind i figured it was the muffler tapping the case, so i got under it while it was making the noise and saw that it wasnt muffler and the truck made the worst noise i have ever heard a truck make. sounded like metal tearing into metal, clanking rattling and every other bad noise that an engine could make. scared the crap out of me because at that point i was laying under the truck. so i jumped up and turned the engine off. stood there thinking... my dad came home later on and the we went over to it. checked oil, trans fluid, all that kinda stuff and everything was fine so he told me to just start it. i did and it ran perfect no noises or anything of course when hes standing there looking. so i drove it back and parked it. didnt start it for a while then tonight i started it. everything was good until i backed up quickly and hit the brakes. started making the noise again. so i parked it and it was still chattering. i turned it off and got my dad to come out. he did and i started it again and it still did it. while we were standing next to it i thought maybe the (flywheel/flexplate i cant remember the difference.bolts to the tq converter...) ? could be cracked or something? crap got inside the dust cover? im not sure so im going to take it off tomorro in the daylight and look. lets hope its not something really bad like the transmission going byebye. (no money) even though we do all the work ourselves parts are $$...... ok well just thought that i would let yall in on my dilemma and cheering up is welcome. i need it right about now... hah. thanks for lettin me cry on your shoulders. later, sam.