Shock absorber and wheel cylinder confusion.

Hello,

I'm having trouble working out part numbers for rear shock absorbers and wheel cylinders. On the diagram ( amayama and megazip) it shows them as the right and left side being different but the numbers only show for one side whichever side you click. So my question is are they exactly the same part and sides don't matter or are the two sides different and in which case am I just not seeing the other part because it's obsolete ?

Here's another weird one.. The shock absorber shows two different numbers but when you type in either number on a UK car part company website and look at the oem part numbers, that their shocks are replacing, both the original numbers show up on each shock absorber meaning they're the same but one number shows up more variety of shocks than the other ?

Also if anybody knows or can check are these the numbers.. S.abs 48531-80401 or 48531-80547... Wheel cylinder 47550-26110.

I thought these were simple parts to find but I'm more confused than ever so if anybody can shed light on this I'd be very grateful.

Thanks.