Jacko,
The side plates on the originals are 3/16" plate with a stiffening rib pressed into 60% of the length. This gives the plate a shallow V shape in cross section. This pressing is present on both the side plate with the pins, and the one without.
The usual problems are that the threaded pins corrode due to being wet and buried in the rubber spring eye bush and the threaded ends also occasionally snap off when undoing a seized nut.

The replacement ones I've seen have flat side plates without the stiffener rib, although they may be made from thicker material; perhaps 1/4" or 6mm. They are probably functional, but appear cruder than the originals to my eye.

I grind out the pin to plate welds, machine new pins and weld them into the old plates then zinc plate the whole thing to reduce the speed at which they corrode.
If you want the original look and can machine them yourself, or know a tame machinist this might be the way to go. I have seen replacement pins advertised online, and you would need to get them welded in.

If you do get them made, make sure the machinist does not use free machining bar stock - it's really easy to machine, and full of inclusions and soft bits which lead to stress and fatigue cracks. Good old 1020 low carbon steel is plenty good enough for the application, and welds well.

That's one of the reasons I personally will not buy things like this online - you just don't know what it has been made from.

Jacko they can be restored, it's just a matter of how determined and/or mad you happen to be.

I prefer a restored old part over a new reproduction part any day, even if it is a whole lot more work.