Neil,
In the first picture, the top cable has partially seized which made the forward and back movement gear selection very stiff, the other cable, side to side movement, was still free. It probably is the same assembly as the 500 and Panda so s/h may be available now but be warned it did go tight very quickly. I was charged 2 hours labour to fit it so probably would have taken me far longer without a hoist.
Interestingly I put in Google search - "How does a car cable gear change work" and found a useful clip about a Nissan gear change cable which was freed by making a hole in the outer sheath, pumping PTFE spray in and re-sealing the sheath - this guy said the Nissan part cost 450 Euros so maybe the Fiat price is not so bad!