There was a thread on them, not too long ago. The rubber ones I have came from Auto Krafters, the poly from Mustangs Unlimited.
ESPO has them in rubber...front bushings and shackle kits...The total will be $75.94 with shipping I may order them later today.
I have a pair of rubber ones that I pressed out of my new springs if you want them. The only thing is that I don't have the thin stainless sleeves.