Do you guys think that front passenger seat cover would fit on the driver's seat? I am thinking since 1st gen has no side airbags, they just might? Anyone tried it before? (mine is '90 if that makes any difference)

It would be nice if they did fit, because there are passenger seats out there that are not in bad shape, but most of us have ripped driver's seat covers.

 

I'm pretty sure that the passenger seat is the same as the driver seat, the main difference being the lower portion, where the switches are.

However, even though the covers are the same, the internals likely differ. The driver's seat has additional controls for height that the passenger seat does not have, so a literal removal of the foam and leather would likely be necessary, in order to swap. [I'm not 100% certain about this, as I've never taken the seats apart]

I highly do not recommend trying to swap the leather covers themselves, as you could damage the old leather on the donor seat during the transfer.

EDIT: Also note that the 1990-1992 LS400 seats and the 1993-1994 LS400 seats are different. In 1993, the design was modified slightly to provide more lateral support, I believe.