HP-how on earth did you get bullets?
Jane-make sure that ball is good and tight. If it comes loose, later on it will break right at the base. If the ball is loose (wobbly loose), throw it away, and get a new one. Read the top of the ball and make sure the hitch and ball are both greater than the weight of boat, trailer, gas, and any other junk in the boat. If the coupler is original, you can match that number.
tip-I have had the trailers come off several times. Each time was due to something that I did. They just don't magically pop off. That hitch is so strong, that the boat will actually flip the whole truck over with out the connection breaking.
When you are lowering the trailer onto the ball, make sure the tounge drops down over the ball, so the trailer doesn't just sit on the ball. Also, I like to use hooks with a safety latch so the chain cannot come off. Some people like to cross the chains saying that they will help catch the trailer. I personally don't bother because the chains are too long to prevent the trailer from hitting the ground. If the trailer should come off, I also don't like having the traier bearing down on the chain causing it to grind through. Trust, I have seen it happen. In that case, the hooks were still hanging on the back of the truck and the trailer did a end-over-end flip.
Also, after you park your truck and leave it unattended, check your trailer connection. Sometimes the trailer has a tendancy to pop off the ball when your not watching-if you know what I mean.