I purchased my 97 silverado about 2 years ago and only put 15K miles on it. I've periodically checked my trans fluid and It looked decent until a few weeks ago. . . now (from the dipstick) it's black with metal flakes in it. Now I'm having to have a partial rebuild. apparently the trans fluid hadn't been changed for a very long time. to save yourself time and anguish. . . MAKE SIRE TO CHANGE YOUR TRANS FLUID WHEN YOU BUY A PRE OWNED VEHICLE!!! don't always trust what's on the dipstick.