Vivitar Flash

I have a Vivitar Zoom Thyristor 2500 flash unit. I used this with my old ME Super. The flash has only one connector on the hotshoe and a cable that went to a socket on the ME Super.
Will this work on my K200d? I note that in the Jan issue of the Mag Thomas Shahan uses a 3500 flash on his K200d. I'm not sure of the difference between the 2500 and the 3500 but from the images I have seen they look identical. Does anybody know if this would work or would I be better off getting a Pentax flash unit?

The flash use the standard hotshoe so does Pentax for their flashguns.
The trigger voltage also seems low enough, Pentax once shimmered through it's confirm with the ISO standard and that's 24 volt link

You can't however not use any automatic modes on the camera with this flash.

Try this site link (Lists most brands and models of flash).