Yes, 90-94 at least, left and right mounts are the same part.
But it can be a lot of work to remove and replace, and maybe the passenger side ones are not as new as they might look before you remove them.
I replaced both on my '91 with OE parts. I don't recall significantly different wear on left vs. right. Dramatic improvement in smoothness after that job (and did the AT mount as well at the same time).
1991 LS400, 180+k miles, no TRAC, no air suspension, no mod's