i got my car the way it is. at least the motor. It is a 5.0. The guy i bought it from said it was rebuilt and had 50k on it. It has GT 40 cast iron heads, e 303 cam, headers, mac cold air induction, 70 mm Mass air, edelbrock upper/lower intake, pulleys, flows, a/c delete, 93 cobra tranny and i think it has gears...3.55? i am not sure. It runs good for the most part and it has been a daily driver for the last 5 months at least, but the engine makes a noticible rattling noise in first and all other gears when i am reving too high. when i am above 2 1/2 - 3 i can hear it and as the rpms go up you can hear it...the ride isnt smooth as it should be as that point and its creatings a vibration. and its not comfortable to take it about 4 1/2. i just drive my car normal. but the car runs good even at high speeds. the rattle will jus be in there consistant and doesnt get worse or better. i can hear it the clearest around 2 1/2 - 3 and a little above. when its reving down from high rpms in 1st ...and i just tap on the gas i can hear it...when below that rpm i dont hear it and it just sounds good. the engine broke an oil pump shaft last year and the oil gauge doesnt work. so the car was run with that problem for a second. when i was trying to figure out the problem it was getting so loud i just turned off the car and we knew it had to be an oil pump shaft or oil pump...after that the car had the sound but i am not sure if it had it before or not because it had gear driven timing and was really loud. so i was thinking it might have bad bearings some where in the motor. but i am not sure because the car runs so good. i use 20 w 50 because i was thinking i might have some bearing problem, but i am not sure if i should be running that or not so i wanted to ask you guys your opinion. i also was thinking it could be something in the heads like i bent valve or something. i really have no idea what the sound is. its not an exhaust leak. it is annoying not having the smooth nice ride my friends and my brother have in their 5.0's. what do you guys think? need more info? thanks for any input and reading.