Jhock wrote:

Thanks to all who responded. I have tried heating the stub with a
torch to no avail, might try the heat with torch, cool with Freon
(computer air blower upside down) also may try mig welding a nut on the
end to give a larger more reliable gripping surface, but will probably
go with carefully cutting so as to collapse the piece. Sure will use
neversieze on the new muffler.

Thanks all. Will post here what finally worked for me.
Jack

Careful with freon-type stuff around hot items.

Burnt freon can produce phosgene gas (of WW1 fame), I'd imagine
anything similar will at least produce some nasty chlorine compounds..

Dave`