Most common parts of a transmisson that tend to break or experience wear ?

What are the most common parts of a transmisson that tend to break or experience wear to the point of needing replacement?

In general makes and models , and in Chevys ?Most common parts of a transmisson that tend to break or experience wear ?
Usually the clutch packs get overheated and wear out before anything, usually because of towing boats, overloading, etc. A good indication of transmission problems is when you change the oil/filter in your transmission, there is usually a magnet that is put in the transmission pan that catches metal particles from clutch packs, broke parts, etc. The less metal on the magnet, the less to worry about. Also its very wise to install a transmission cooler to keep the fluid cooler when towing or just hot weather driving. Heat is the #1 enemy in a normal transmission use.Most common parts of a transmisson that tend to break or experience wear ?
cluthes and bands