Full bench seat? or a two plus one ?
There is a kit to adapt a walkthrough to a two plus one ,left hand/ right hand specific , but think they are reasonably rare .
Probably best fabricating something yourself if your that way inclined , last one I seen went for £400 RHD , for essentially a few bits of metal !
There is a back piece and two between seat braces from memory .
there was one for sale on here not ages ago , think it included seats , might be worth a search in for sale section as listed original part numbers etc .
Chico