you have to heat them up with a torch and then smack the housing with a hammer to jar it, the bushing is most likely corroded in place.
Before I do this however, I would check and make sure your bushing doesn't have a tang that fits into the slot, I've seen some that have them and some that don't have them. Verify this before you heat and smack the housing to get the bushing to turn you might have to pop the bushing out and replace it.
If you have to remove the bushing to replace it, youll have to break the ball joint loose, it is a taper fit between the bushing and the ball joint that is what holds it down in place. Once you get the taper broke loose it should pull out easy long as it is not also corroded into the I beam.
"Old Blue" - '56 Fairlane Town Sedan - 292-4V, Ford-O-Matic transmission, 3.22:1
'63 Belair 2dr sdn - 283-4V, Powerglide transmission, 4.56:1
'78 Cougar XR7 - 351-2V, FMX transmission, 2.75:1 9inch
"Bruno" - '82 F150 Flareside - 302-2V, C6 transmission, 2.75:1 9inch, 31x10.50-15 BFG KO2