AFAIR there is a bracket or clip securing screw hole on the
shock absorber which secures the brake pipe. If
it can be secured in either of two positions (corresponding
to left or right) then it should be ok either side.
Many parts of the Uno, Cinquento, Panda are the same,
can't speak from personal experience about the 128.
Did once have a 126 but that had a leaf spring on the front.
For safety reasons it is probably advisable to replace in
pairs, the spring rates could be different, and with different
degrees of aging.
Absorbers may fee stiff or even gritty until you put
sufficient pressure on them, then they turn freely,
worth remembering if you are checking them out in a
breakers yard.
It's a good idea to give them a good clean down
before an MOT (just to get rid of encrusted road
dirt, not to hide traces of oil you understand), you
need to do this anyway to inspect the rest of the
braking system, pads, caliper for leakage, split CV
boot not shedding moly grease everywhere.
Replacing the shockabsorber water shield and bump stop
can be a pain in the arse, there is a learning curve.

I just found out myself that the shockabsorber of a 128 is totaly different
from that of a Uno.
So i have to surch for one of a Uno. But thank for all the advice.

gr Nico