Here is a diagram of the rear bumper for a wagon:

http://www.volvopartswebstore.com/showAssembly.aspx?ukey_assembly=236777&ukey_make=865&ukey_model=11966&modelYear=1995&ukey_category=7875&ukey_driveLine=478&ukey_trimLevel=11059

There are no shocks, but there is a foam like structural piece that may be crushed. Remember, what you see on the outside is a 'cover'. Removing the bumper cover to examine damage is quite a job as the bolts are very hard to get to.

If the tailgate is bent, it was a very hard hit. I would look for a tailgate in the correct color at a pick&pull.
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My back feels better when I sit in a Volvo seat