As I recall, the bushings actually fit into the welded tube shown in the picture. After I knocked out the rubber, what was left was the outer metal shell of the bushing stuck inside the welded tube. I split the bushing shell carefully with a hacksaw in several places then knocked the pieces out with a cold chisel. A quick cleanup and the new bushings knocked in with a bit of effort.
A tip I read while reassembling the refurbished radius arm to the car was not to tighten up the bolts holding the radius arm until the suspension is setting at ride height. If you tighten everything up while the suspension is hanging off the car, when it gets lowered, the rubber bushing is likely to get sheared (or fail a lot earlier) as it gets put under a lot of torque as the suspension settles into the road position. Could be just a old wives tale, but I thought it made sense at the time.