This post has been transfered from the post "Wheel variations".
There have been at least two variations of the 796 Trailer for the Healey Sport Boat.
The one on the left is the common one with a third wheel at the front. The one on the right is much rarer and on this the front 'jockey wheel' has been replaced with a skid.
I suspect that this was towards the end of the production and was done as a cost cutting exercise.