Ok, I am finding very little info about this swap, scouring google, and this and w-body forums, I still find very little info on swapping 6th Gen Monte Seats into a 5th Gen. Only info I found was "Just swap the rails and they should bolt in" heh, yeah right.....

First the 5th gen rails do not bolt straight up to the 6th gen seats, I had to drill two extra holes to get the rails to mount to them, and then guess what? The seats once in the car, sit waaay too low, and way too far forward.

With the seat all the way adjusted back is just enough to make driving possible. Plus I had to remove the side plastic piece because the rail hit the back side of it, and also doesn't clear the floor.

I know some people on here have done this swap, and I'd like some information from the people on how this can be done.

 

I recall reading about that once too. However I found some nice seats from a 98 Monte Carlo and didn't need to make the 6th Gen to 5th gen swaps. I think I read about you could mount the Tracks from the 5th Gen under the 6th Gen seat. I am not sure why you can't make it work maybe the Console will need to go. Sorry I can't help any more than that.
One thing is true the 1995 Monte Carlo back seats won't mount into the 1999 Monte Carlo the same way. I was kind of surprised they had modified the mounting for it. So if this was an issue on the 5th Gen then there could be a change on the 6th Gen seats that might have been changed.