I'm looking to see if anyone has seats or seat covers for a 1992 SR5. I'll post pics of what the material looks like. I only need the driver's backrest cover, but I'll buy the whole seat if I have to. I've been looking for these covers for years,
and can't seem to find ANYTHING out there. Please and thank you!

 

I’ve been down that road with my old 4Runner. Original truck seat covers are hard to find, but Wet Okole has been a lifesaver. Their custom-fit neoprene covers might not be an exact match for your SR5’s material, but they offer great protection and a snug fit. I went with them after years of searching for OEM-style covers, and I’m really happy with the result. They’re easy to clean and durable.

 

I think your best bet is look for a company selling oem-grade auto seat fabric and have someone sew in the panel(s)
midwestfabrics.com is one, but there's more