Catalytic Converter Replacement question
Got a question about replacing the cats in my truck.
1999 F150 V8 5.4
Trans Code U - 4R70W
I had my truck at Ford the other day as I tend to like my local dealership's service department. I had them check out the truck (during an oil change coupon offer) for potential issues due to a road trip I am taking next week with my trailer. I mentioned I wanted the exhaust leak checked out. They found the leak which was located in the area of the Cats. I went into the shop and physically saw for myself the rot. The service adviser said he it would be better to have a muffler shop replace the cats as Ford would not be competitive. We went over a few other things that needed attention and I authorized the repairs so there would be no issues for the drive. The mechanic mentioned to me in the bay the truck was one of the better ones for that age range and can see that it is maintained regularly.
So I am looking up cats for this truck. It seems the cats in stock are for 4R100 trans. I called a few auto parts stores from the big chains to local guys. Everyone asks "Are you sure you don't have a 4R100 trans?" One place said they didn't have a listing for my trans for that model year. One place found them and quoted me about 70% above the cost of what I can find for the 4R100. From my understanding the 4R70W seems to be a pretty common trans like a 5.4 V8.
At this point, am I better off just finding a "good muffler shop" to replace the cats? Also would I not see a code being thrown by the O2 sensor if there was leak in the cats? I have no codes or CELs. The truck runs great and gets descent gas mileage. I just can't stand the leak noise since it is in the cab area. Like I say, performance sound by mother nature!
Please give me an idea of what direction I should investigate. Thanks in advance.