We use the CU/AL wire nuts for temp repairs only, and recommend the customer rewire. The AMP tooling is the only approved method of permanent repairs; however try to get this tool in the box to make a proper splice and you will qualify for doing brain surgery. The use of pigtails can make more problems occur. Just moving the existing alum wire can damage it. You may want to check some of the back issues of news papers there are some real horror stories out there.
We had one here in North Jersey last year.
The home was a total loss and the family never made it out. They said the wiring was mixed copper and alum. So be cautious when you take these jobs.
LK
