Morning Pam,
The water heater bypass is located on the back of the heater. Which means the bypass is actually located/accessed from inside the coach. Sorry, I can't remember if the heater is under the bed or couch, but you should know where it is. As for putting "pink" anti-freeze in the lines, once again, your gonna have to check to see "IF" your 1950 has the winterizing kit on it. For this you need to locate where your "water pump is and see "IF" there is a valve on the ingoing line, if there is there should also be a short piece of hose that is not connected to anything on the one end. This end would be stuck into the bottle of pink and with valve turned to draw from this hose, turn water pump on and then turn on faucets one at a time till they run pink, proceed until all faucets run pink, then do shower(s) interior & exterior, and commode (also leave a small amount in the commode once you close the valve. Gosh, hope I typed all that correctly, and you can understand it. Been a while since I had the 1950 so not posative about locations of things anymore.