Here are some pix of the third row suburban seat I have.
It looks like the pictures you sent.
The only different thing i see is the side grab handle? that connects top to bottom frames at the sides.
My seat has flat pieces of metal, all other seats I see have a tubuler bar?
Thats what makes me believe its from a 55-59 suburban or other make?
Suburban Third row seat / ASuburban third row seat / B 
