They have a limited lifetime warrenty. When they are worn out you can get replacements under the warranty. I never tried it before but I plan to in the future.

MONROE SHOCKS & STRUTS :: Safe & Sound Guarantee

 

Very interesting. Do Super Duty's count as light trucks? And how can they expect them not to wear out, heck the MR.tire near my house has a display from Monroe recommending replacement every 30k miles.

-for a metal bodied shock a coat of POR15 when they start to sprout rust will do wonders!