With any older flash that predates the digital revolution, the thing to watch out for is the trigger voltage. This is the voltage across the synch terminals of the flash when it is fully charged. Some older flashes have a trigger voltage of 300 volts or more.
High voltage was not a serious problem on older film SLR's, since the synch mechanism in the camera was often a mechanical switch. On a modern dslr, however, it is all done with electronics and such high voltage can fry it.
If you have a small digital multimeter, its easy to measure the trigger voltage. Just charge the flash up and touch one of the meter's leads to the center pin of the flash's hotshoe and the other lead to the ground connector in the side of the slot that slides over the lip of the camera's hotshoe. If your meter shows more than about 25 volts, don't use the flash. New flashes, by comparison, are usually less than ten volts.
You can get a relatively inexpensive adapter that will fit on your K10D's hotshoe and give you a PC connector. Search ebay for "nikon as15". This device offers no protection for your camera.
NIKON AS-15 hot shoe D3000 D40 D40X D50 D60 D90 - eBay (item 200553843530 end time Dec-18-10 09:27:20 PST)
You can also get a Wein Safe-Sync adapter. This device also fits on your hotshoe and provides a female PC socket, but it also reduces the voltage that is presented to the camera. With this, you can safely use older, high voltage flashes with a dslr. Search ebay for "wein safe sync"
Wein Camera Hot Shoe to Flash Hot Shoe Safe Sync PC NEW - eBay (item 140478401841 end time Dec-14-10 11:42:19 PST)