Don't quite know them as seat bushings. Sounds like you are describing shackle bushings. There are 4 on the rear and 4 on the front. If that is what you are looking for check under shackle bolts/bushings. The aftermarket sets are plentiful. I got mine at NAPA for my 49.
If there are such things as seat bushings then the above does not apply. But I've never heard of them as such. Then again I don't get out much.


1949 Chevy 1/2-Ton
"Sedgewick"
In the Gallery
1989 Caprice