If I remember, your second gen seats have a frame that runs parallel to the floor and all eight bolts (four per side) bolt directly through the floor vertically.
The third gen seats have two vertical mounts in the front that are perpendicular to the floor and two horizontal mounts in the back that are parallel with the floor. You're going to have to cut and fab up an adapter of some sort without drilling new holes in the body. The adapter wouldn't be that complex, just some flat bar. Let me know if you need some ideas.
FYI, the 4th gen seats are much more cumfy than those 3rd gen ones.