Jerry, there are a couple ways to determine a Dwyer or Z-spars mast. A Z-spars has a flat aft face of the mast. It also has a mast foot casting that looks kinda like the vanes of a heat sink, with internally routed main halyard which exits the mast through the casting and a pressed in sheave. There is a corresponding cast aluminum deck plate.
A Dwyer mast is oval all the way around, and the mast foot casting is low profile. There is a U-shaped plate bolted to the mast foot, and a hole in the fore and aft part of the downward bent flange along the side of the plate. There is a corresponding upwardly bent plate mounted to the deck. SS 1/4" pins go through the holes fore and aft - removing the fore pin allows the aft pin to act as the hinge.
A guy at my club had a mast raising incident on his Z-spars mast this spring, and he broke the hinge bits on his foot casting and deck casting. Z-spar castings are available from
www.rig-rite.com, but they will look significantly different. To replace the casting, you will need the casting, which includes the foot, and the deck plate, as well as a new 1 1/2" or so thick block of starboard. You will also need to cut a window in the side of the mast to allow the main halyard to exit, and buy a trim plate which is riveted into the new exit hole. You will also need to buy a stud block that bolts to the new deck plate. The deck plate has flanges with holes to receive the stud block, and thus becomes like a deck organizer plate. The plastic starboard spacer block goes under the new deck plate - it's purpose is to space the mast up to the correct height so that you don't change standing rigging lengths, because the new foot casting is not as tall as the old foot casting.
As for a new forestay, I'm assuming that the old one is parted or broken. If the forestay has parted, it's not so easy to send the old and have it measured and replicated. In that case, it's probably best to just order a new one from Rudy at D&R Marine. If not, you could send the forestay off to any manner of rigging specialists. I personally have worked with Annapolis Performance Sailing, and they are solid. Others have worked with West Marine in Annapolis, or Sail Care, or Cajun Ropes, or even here at Sailboat Owners (not sure if SBO does standing rigging or not.)
Let me know if you need any other direction. I have a Dwyer mast on mine, and I did much of the repairs for the Z-spars on my friend's 192.