should i replace the rear shoes on my 97 chevy silverado z71 if their cracked or...

[chris]

...just leave them as is? the shoes look new
but they have a crack in them
its only one shoe on both sides
truck does alot of hauling the heat musta did it
shouldi just leave it or replace them?
look i didnt do it
the great people at firestone installed these
and claimed it wasnt their problem