Answer:Maintenance is simple, you can use any grease you like as the joints are only slow moving and no heat involved. Under very dusty conditions a couple of pumps on the grease gun every 1000km of dusty roads or so in the main body and the vertical bolt that holds in the universal joint. This just pumps out the dusty grease in the ends of the joints and refreshes with clean grease.The pin can also be luricated by using silicone spray even though there is a grease nipple. The reason I suggest silicone spray is grease will collect a lot of dust and then it dries up making it gluggy and hard to put the pin in and out. Silicone is really easy to just wipe of and spray a bit more on to make it slide easily. Use grease if you prefer.

Answer:When choosing a hitch it is somewhat depending on your use. If you are going to do a lot of beach work I suggest a Galvanised unit or also if you live by the sea. Salt air will cause faster corrosion. Galvanising is a superior corrosion protection.The Zinc unit is more suitable for painting if you require to colour code to suit your trailer. The zinc is also quite good at rust prevention but does need a little more care. I suggest with either of the units that to keep in top visual condition you can spray a little WD40 or lanolin oil on them to keep them looking good, however not needed. All that said both hitches are exactly the same except for the coatings.