First of all sorry for the poor pics but it was dark by the time I took the pics.
Here's a pic from a 95 DI:
As you can see the rails are bolted into a frame that came on a 94 and 95 DI. In 96 thru 99 they removed the frame and welded them to the floors.
Here is a pic from a 99 DI:
Here is a picture from a 94 RRC:
It looks like you could bolt the seat from the 99 DI into the 94 RRC and vice-versa. I haven't done it so I'm not 100% sure.
Now, if you look at the next pic of the 95 DI it looks like you could remove the seat and rails from the frame and they might align with the 99DI setup (and vice-versa) but again, I haven't done it so I'm not sure.
What I would do if I were you Chris is remove the seat from the 95 and turn it over to see what the problem is. It could be that the cushion is split or that the diaphragm under the seat broke. You can replace the mesh with a new one made out of rubber from Exmoor
http://www.exmoortrim.co.uk/catalogue/detail/123-re-trim-kits-foams-diaphragms/flypage/3887-discovery-1-seat-diaphragm.html?sef=hcfp or a canvas one for $25.
If the cushion is split you can buy a used one or a new one from Exmoor
http://www.exmoortrim.co.uk/catalogue/detail/123-re-trim-kits-foams-diaphragms/flypage/804-discovery-i-seat-base-foam.html?sef=hcfp
In any case you have to remove the seat to see what the problem is.
Just an FYI for anyone who wants to change the rear seat on your DI over to a RRC style seat with the armrests, it IS possible. They fit perfectly in the back of your DI. I have them in the back of my 95 DI and my daughters love the armrests.