Looking at the photograph on the right it looks as if it bush has a metal bush in its middle, if this is the case it is definitely not the correct item, also the centre hole in the flat nylon washer should only be just big enough for the radius rod to pass through it so again it is not the correct item. It might be a damaged nylon bush which has been reused as when I have stripped a number of 1500 rear axles I have often found that the rubber bush has punched a hole the size of the rear axle mounting hole in the nylon washer.
I have stripped a number of rear axles which have had polyurethane bushes fitted and I have noticed that they have started to take up the shape of rear axle mounting hole, so my assumption is that the new Superflax polyurethane has been produced with this shape either on purpose or by just copying a used bush. Can you please measure the diameter of the raised section on the new bush and see if it is the same size as the hole through which the radius rod goes which is 1.25 inches. The mounting plate is about ¼ inch thick so the raised section could be up to 1/8 inch.
I have taken a number of photographs that show the size of the Radius rod hole mounting on the axle, How a nylon washer fits into the mounting arrangement if a rubber bush is being used and the final photo shows on the LHS a old bush that has started to take up the shape of the mounting arrangement.
I will also post once again the text that shows the fitting details.