Wolfman said:

Last time I saw Kenny Baker and Dave Prowse, they were both in wheelchairs.

I don't think David Prowse is in a wheelchair or otherwise has any trouble getting around (unless it is a very recent turn of events). I saw him in a YouTube video from last year where he puts on the Darth Vader costume and has a "lightsaber duel" with a fan:

Are you sure you're not thinking of Peter Mayhew? He needs a cane to walk and is sometimes in a wheelchair.