40/20/20 are kinda hard to find, but I did manage to find a set for my 95 RC. I haven't got them in yet, but they say you have to find a crew cab and then the mounts will bolt up. I got a crew cab base and then the seats out of a ext cab.
I have seen SD seats, but I am 5'11" and there is no way I would have enough room. Saw a pic of Dodge seats in a ext cab- looked like they might work?