Ransomes Ajax Mk3 Inverted Arms

If you zoom in , the arms are inverted and do not fit in the slots, hence the covers bend inwards.

Which model do these arms fit ?  This is a mark 3 .

It is as if the arms have been incorrectly welded ?

Any help welcomed please 

Is my query too vague ?  Or do my photos not make clear ?  The upright arms need to be curved the other way to fit. I have 2 sets like these. Which model do they fit ? 

I also have 2 sets of arms that do fit as the arms are curved inwards.

Thanks all

The answer is: it fits the Atlas.

I believe the inverted arms were used on the Mk1 & 2 Ajax only. The Atlas and Ajax Mk3 had the arms the other way round.