Thanks for all the suggestions and advice. Lots of good info here.
I put the butts in a large foil pan and covered with heavy foil. When I discoverd my foil pan would not fit in the cooler, I put the pan and double wrapped brisket in the oven. I turned the oven on and heated it to about 190 (approx. temp of meat when removed. Turned the oven off and left the door closed.
My oven has a display that shows the temp when you turn it on to preheat, so every couple of hours or so I turned it back on to see what the temp was. If it looked close to 140, I turned it back on for a few ond off again when the temp looked closer to the original 190.
This worked out well and when time to eat everything was still hot and delicious.
OTS Kettle, UDS, Sam's Gasser