Most seats attach just below the slide mech. An Aluminum adaptor plate should make the seat you want attach to your floor and/or swivel.

https://www.vanning.com/threads/ubb...l-seats-anyone-seen-them.html#Post754790


SUNSHINE VANS-VAN DIEGO
ADRENALIN BY THE GALLON & CHASIN RACIN
ONE FOR THE DIRT & ONE FOR THE STREETS
'93 CHEVY G30 454 4X4 SPORTVAN EXT 146" WB
'92 CHEVY G30 454 BEAUVILLE EXT 146" WB