I bought a LHD S40 wiper linkage assembly (Volvo part 30850294), and then butchered it for parts in an attempt to improve my RHD assembly. This actually went really well, but it required a bit of work.
Originally I was going to write an article for this, but I lost almost all the photos π so here is a condensed version.
The original spindle mounts (seen below) were a simple plastic assembly with the spindles themselves having a recess in the middle to hold grease and reduce friction. The new assembly, the LHD one, had no such recess in the spindles, but the spindle mounts instead were bored larger, and had bushings pressed in at both ends. The OD and length of the spindles is the same in both instances, but the LHD spindle mounts are angled differently (a mirror image basically). This means you can't use them, but you can use them for parts π
So I tore everything down and mounted my original RHD spindle mounts to the lathe, using a snug fit drill bit to centre them (you can't see it but it's what the chuck is holding), and using a bolt and a cable tie as a drive dog.

Don't hate on me for my shadetree lathe setup but it worked fine for this operation.
I then just bored them to match the LHD bores, and pressed the bushings in. This worked great, one of them was not as interference as I would have liked so I used a bit of perma-loctite to keep the bushing in place. It probably didn't need it but I don't want any risk of the bushing spinning in the mount.

Looking at the above photo of a LHD assembly, I was able to take the linkage that runs between the two spindles, as well as the rubber dust boots that sit behind the ball joints (mine were failing or missing entirely).
I used Sachs high performance grease as that seemed very similar to what Volvo used.
I re-used the original thrust washers and wave washers as the new assembly used slightly thicker ones and it would mean having to shorten the spindles on the lathe which seemed excessive given the old hardware was fine. I also took the o-ring and circlip from the new assembly.
In the end it all worked really well! The spindles have no side-to-side play and feel just like they did on the new linkages, before I tore them apart.