Wife seeking answer about Barn Doors vs. Tailgate for '88 Suburban..

[OverRunWithSons]

We bought a 1988 Suburban and the tailgate has an electric window which is SHot, destoyed, rusted and worthless. We want those maintenance free Barn Doors put on instead. Can we EASILY change this by going to the Junk Yard and finding some decent Barn Doors, WHAT ALL IS INVOLVED? And how can I find out what Years the Suburbans have to be for the Barn Doors to fit our 1988 Suburban?? Is there a good book out we can get our hands on about MODIFYING our 1988 Suburban ?? We also need to install a 3rd seat as this one we bought only has 2 seats. I wonder if the holes are already under the carpet or my Husband has to do some drilling and bolting to fit our 1978 2nd Blazer bench seat into this '88 Suburban ?? I am just the wife seeking as much INFO as I can to help him with these jobs. It seems the Suburban books don't mention any of this stuff. Thanks!!