An inactive member pointed them out to me on e-bay about this time last year. They are generic replacement seats as far as I know... no real aplication.
http://67-72chevytrucks.com/vboard/s...d.php?t=136065
I took a trip south a few months ago, about a 500 mile round trip, me driving and a hottie riding shot gun, I never had any back pain...which is a feat in it's self... and as far as I know, her back wasn't hurting... so i'll say this was a good upgrade.