hi all,
what is the life expectency of a catalytic converter?.... i read the post by sideburns that stated the telltale sign of needing it to be replaced was the rattle of doom... how bad does the rattling have to be?.... mine will rattle at cruising speeds (60+)

reason im asking is that im suspecting that the exhaust system is the culprit of a vibration humming noise im getting at cruising speeds (is different from the one i posted about before, which was u-joints).... this one is a lot less noisy.... but irritating just as well....

the muffler was replaced last year.... and i brought it to the shop last monday and they found a leak at the cat.... right before the muffler and welded it up for me.... but the buzzing is still there....

also roughly how much are we talking about for a new cat, how much more for a freeflow cat?

thanks
JQ

'93 4runner automatic, 4x4, 4.88 gear, almost completely stock