I removed the front Y-pipe and cat from my DD and installed it on the youg(est) one's 80. The cat on that one was swiss cheese. Lots of rust grinding, and had to reuse the Cat-to-Cat gasket, because Toyota has deemed it unnecessary to maintain. Bummer. Fortunately, it was good enough to reuse for the near term, while I search for a replacement. Both mine and hers have the OEM exhaust parts, but hers were eaten away; odd for a NC truck, but it had been in the mountains for a spell. Had to replace the front rubber cushion as well. It was there, but in two pieces, so not exactly functional.
Hope that cuts down on the redneck appeal from the exhaust, for now.
I had only planned to replace the front cat, but after everything was done, my "last look before turn over' inspection revealed the rear cat now has pinholes, so that's now on the menu for next weekend. That one's really rusted; I think it's going to be a cut out removal. Bonus is I get a new die grinder.
I bought a new Y-pipe and front cat from Magnaflow; the other 80 gets all my usable parts when something breaks. Mine gets new ones; I'm building a ship of Theseus.