I only know GM part numbers. Have no idea of their equivalent aftermarkets.
You didn't specify for what application, but here's what I have for part numbers on an 85 442. And most likely others.
(2) 330951 #6 upper
(2) 25500592 #7 upper
(4) 377801 #6/#7 lower
If you're seeking poly bushings, there's nobody I know of that sells just partial kits. Most of the time, you buy frame "kits" and radiator support "kits" or full on complete "kits". I know you can get the OEM style rubber bushing repros sometimes one at a time, but not the polys.
Did you try asking any of the manufacturers if they had any individual or partial kit purchases? May not be worth it as they might be just as much individually or in a back half kit than buying the rest of them together. I don't know.