I think if you have access to/or can weld you can make any seat frame work in the your K5.....couldnt find any K5s but I could find a lot of pre 73 Blazers that have did it both ways fabrication or purchasing the Procar seat bracket mounts..........
http://67-72chevytrucks.com/vboard/s...d.php?t=639176
http://67-72chevytrucks.com/vboard/s...d.php?t=616012
http://67-72chevytrucks.com/vboard/s....php?p=6532114