Well usually when the deck is gone it's just not feasible to replace with new. A good welder can do a lot
for an old deck if it isn't too far gone. It's really hard to find a good used deck because you would need
to find a repairman that has a lot of junked mowers sitting around. Then you would have to find a junked mower of the same brand/model to fit your mower. If you do happen to find one same as yours, it might not have much more life in it than yours does. That's the down side.
On the other hand if you found a deck of your type mower that the engine died prematurely and the deck
didn't get much use, that would be ideal. So if you know where there is a repair shop with a lawnmower
graveyard, it might be worth a shot. Be sure to take your make and model info with you or even better,
take your mower with you to make a match