Thanks Tommy,
I'll have another closer look tonight. I only got this vehicle as a parts vehicle on the weekend so haven't looked too close yet. What I was told was that it came out of the army like this and has not been changed.
So the bar on the ground is definately original and standard (although the inside corners cut out to fit SUE winch - done in service) it is heavily galvanised and does look thinner steel than the wide one.
The wide one is rusted, I'll have to check if there's any gal, I'll have a real close look for weld joins, and the bolt holes are in different places.
So it is an odd one and hard to work out.
Will look tonight and add anymore info.