My car is a RHD car and I’m trying to try some Chinese replacement mirror cases but they all say it will not fit RHD mirrors apparently it’s different.

Can anyone tell me what exactly is the difference between the LHD and RHD mirrors? Is there no way to adapt or modify a LHD cover to fit the RHD mirror unit?

 

Yes, LHD and RHD mirror setups are different because the mirror furthest from the driver is convex, allowing the driver to have slightly more field of view from the mirror shape. The driver's side (irrespective of LHD or RHD) is flat (no convexity or concavity). Hence, the mirrors aren't really interchangeable between LHD or RHD. You could possibly live with having a wonky mirror setup, but that's up to you.

Good luck!