Wow, thank you so much. So you recommend changing both catalytic converters?
Its up to you really.
Above is my experience with a first generation v6
I ended up doing the job twice because I was not complete the first time. The pictures are all gone and I cannot update them since the forum makeover but in my case the converters dissolved and clogged the downstream cats (there are four total in my car). Since I only replaced the upstream oned the downstream ones eventually clogged and destroyed the upstream ones as well.
The recommendation for the "correct" fix is replace all the catalysts (4), oxygen sensors (4) and fix the reason why they died to begin with. In my case it is bad/old coil packs and spark plugs. Catalytic converters do not die, they are killed.
Improper combustion leads to their demise.
I was planning on keeping the car for years to come and I was also doing my own work. For me to do the job I described cost me just under $1400. If I would have had it done the estimate was $4700, more than the value of the vehicle.
Keep in mind that a new car payment is around $300/mo so if you will keep it more than a year ($3600 in car payments) then it may be worth it.
That motor (3.7L) also has the water pump in the timing cover so if you haven't done that replacement yet it might be an important consideration to make before you decide. When the water pump fails it fills your oil with coolant and motors don't tend to like that.
Sorry it is not the greatest news but I would rather you go into it know more rather than less.