I had a similar problem with my DS. The OEM latch went south and Newmarket could no longer supply.
Went to Home Depot or one of those places and bought a Brass Sliding Latch used on cabinets etc. I mounted at top top of the shower door on the inside so it is not visible from the outside. Have to reach up and unlatch by sliding the bar back and rematch once in the shower.
Works good an no more rattling shower door. If I can get a photo, I'll PM it to you.
Dennis & Carol
2003, 4006, 41' DutchStar,
Spartan, ISC 8.3L W/BanksPower - 2013 Honda CRV, BlueOx Baseplate, Aventa Bar & Patriot Brake. And the 04 Bird, Sunshine Car.