i need suggestions... when i down shift from 4th to 3rd it grinds like crazy.. like my tranny is about to blow...but if i shift it quickly from 4th to 2nd and into 3rd while still on clutch and it does not grind... what can the problem be? any suggestion would be helpful...thanx..

Bad synchro's would be my guess.

Definitely the 3rd gear synchro.

http://www.pennzoil.com/products/gear_oil/syncro_fluid.html
Has helped a lot of people and saved getting a new tranny.

If it has low miles...a tranny shop could repair the 3rd gear syncro for ya.

If it has high miles...just get a new one.
http://www.car-part.com/