Been there.

I presume you have already tried using a chisel to whack outward on the metal flange that protrudes a bit to no avail.

There are 2 methods that both worked for me:

1)
Drill a hole through the metal face (to one side of the bolt hole) on one bushing so that you can use a big punch to knock the other bushing out from behind. Striking from behind seems to be so much more effective.

2)
Get a bigger chisel and a bigger hammer, and force the (now bent) flange on the bushing toward the center of the bushing until it is cut or bent sufficiently to allow the extra clearance for the bushing to pop out. This method is more violent, and purges excess frustration.

3)
My cousin used a torch, which made a spectacular fireball as the rubber bits burned. This is more entertaining, but I'm not sure it helped that much over the drill method. Once the rubber burned away, he was able to 'strike from behind' with a chisel.

Actually, pressing them back in is the real trick. Pushing on the faces does not work (even with a 50 ton press!) because the 'tubes' on the 2 bushings hit each other before the 'outer rings' are seated in the arms. The rubber compresses before enough force is applied.(hard to describe, sorry, but you will see if you try it.)

I struggled with this problem on the first side, but I can save you the grief!
The perfect tool for driving in the bushings is a Steel Pipe Coupler for a 2 inch pipe with threaded plug in one end (plug is just to strike upon - Home Depot).
This is just a hair too tight, so you need to grind away the first 1/4 inch or so of threads (I used a Dremel tool), then it fits perfectly. If you happen to have a giant socket set, the right socket would probably work too, but this is way cheaper. You can either strike the coupler with a hammer, or press on it with a big vise.

It helps to use some lithium grease. Ordinary grease should not get on the rubber, because it will damage the rubber over time.

One last thing!
Note that the orientation of the bushings matters upon install. The front orientation is different from the back. Do you have a manual that covers this oddity?

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1986 300E 5-Speed 240k mi.