Summit's advertising some in their catalogs. Apparently they've picked up the Pro-thane bushing line, because I see the name everywhere in their Chassis section of the catalog. They're selling two tubes of grease, the difference being the size, and they say it's meant for installing poly bushings. Can't remember the name offhand, sorry... but the Summit tech guys should. 1-800-230-3030 ..
Of course I'd also like to know other sources
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html