What is scraping my flywheel to cause a rattling noise in my 1987 Chevy caprice?

It rattles when I turn the ignition and when I put it in gear but I drive it's quiet but if I come to a complete stop or slow down it rattles!

If this was a manual drive car I would suspect the clutch release bearing or some thing loose within the bellhousing.

check all the bolts on the inspection plate and make sure they are there and if so, tight. Check all covers around the starter, making sure they are tight and snug. If you can put it on a rack, have it started, out of gear, and go under and listen for where the rattle is coming from. Might be a muffler or exhaust hanger or exhaust pipe out of alignment. Rattles can come from anywhere. The best ones are from little hands in a car carrier in the back seat. If the sound is from inside the bell-housing, it may be a throwout bearing as Paul suggested above or a clutch tooth spring having let go. Remove the inspection plate and do the sound test again while it is up on the rack.

Im haveing the same issue..... went to the local chevy dealer and they said its the fly wheel cover /is rubbing that was a month ago and just noticed it again this morning should a new fly wheel help or will the same issue happen

he flywheel is bolted on solid. The inspection plate may be lose or damaged some way. If you can remove it and check for worn spots. Make sure it is not dented or bent in any way. Bolt it back on and make sure it is tight.

I went to meinke newmuffler tail pipe,they say it is the catalytic convert.making rattling noise,we put in o lift and he point it out to me.

So your question was what is scraping your fly wheel to make rattling noise and a muffler shop puts on a new tail pipe? Why did you think the fly wheel was being scraped? Loose tail pipe and or muffler hangers can wear out due to element exposure and heat/rust, and that will cause rattling underneath. The cat is in the area where the flywheel is located, and if the cat is starting to fail, or is loose or if it was welded and the pipe is rusting out, will cause rattlings. Lesson, go to an experienced trusted mechanic to get a true and complete diagnosis. Some times a good garage may cost more but they pay and keep good trusted workers and remember, you always get what you pay for. Pay less, you get less.

They say the catalytic need changing worn out.i don't have to have emission or catalytic convert on my 84 Chevy.

All vehicles from the late 60s on ha or have some type of emission (smog) control device. Cats came on the scene around the late or early 80s. If you don't have them than someone removed them. Catalytic converters just plug up an quit working. There is no charging to be done. Change yes. If it is worn down and not doing it's job, it may develop a rattle like small marbles lose.