I second the cutoff tool. I think using a puller is probably a waste of time and using a torch would be my last resort. A plasma cutter would work well but you have to be oh so very careful.
However, I would cut it parallel to the spindle so if you go through it is in line with the stress of the weight on the spindle and does not allow a crack to spiral around the spindle if it comes to that. Even so, I would be very concerned about the damage the excess heat may have done to the spindle. Look for heat stressed metal on the spindle evidenced by blueing or scorch marks.
Several posts gave good instructions about cutting almost all the way through and smacking the crack with a chisel and BFH. This problem is sort of similiar to trying to remove a carrier bearing on a driveshaft. They never "pull" off easily and if they do, that is a problem in and of itself. Most backyard mechanics will use a torch if they have it, but the cutoff wheel is the way to go here.
I don't as of yet have an air powered cutoff wheel so I use a dremel tool with somewhat oversize fiber reinforced cut off wheels. Believe it or not, I have used a standard dremel on my deuce mostly to clean up threads that have been burred or to cut small hardware that I cannot get loose. That size tool is good to about 3/8" inch and is remarkable as to what it can do with a steady hand operating it.
I hope you get this truck back on its wheels and moving under its own power soon.
Life is just not the same without your deuce carrying you along.
RL