3-5 yrs here. Usually where the tailpipe meets the muffler is where mine stats to rust.

 

Mine were 96 each. :-)

 

thanks, now come and intall the damn things on my truck for $96 each

 

For what it's worth, here's something that has worked for me since I had my Flowmaster system installed with welded joints. Pick up a spray can of CRC ZINC IT at Home Depot and coat all the welded joints making sure you get the full weld all the way around. This stuff is highly flammable so use on cold exhaust only. Fumes can be harmful so use eye and breathing protection. If rust has already started, get some coarse steel wool and get to as much bare metal as possible. This is not an easy process when you are on your back under the truck, so if you have access to a shop lift, it's your best option. I stress again, USE EYE AND BREATHING PROTECTION if you do this.