Lee,

They are upside down shock absorbers, the telescopic rod hangs down into the strut body, the end of the telescopic rod is threaded and screws into the bottom of the casing, thats the arrangement shown in the pic and the arrangement is more commonly used on competition cars.

You can get conversion shocks, which have a threaded strut casing and accept an uprated damper, the dampers in these tend to be vertical with the body of the damper sat in the strut body and the rod pertruding upwards fixed to the top mount.

The damper is retained by a cap on top of the strut body, these have no phosi bronze bushes as all the work is done by the damper itself.

Both options strip to their component parts, the internals of the dampers are a little more difficult to get at......lol

HTH

Ian