Definitely need pics or a very accurate description. There were several versions made of the NWTF 870. Some had wood stocks, some laminated, some synthetic camo. Some guns were matte black, others completely camo. I don't know if they were all 3.5" or if some 3" were made. It appears different barrel lengths were made.
Edit: I overlooked the 25th Anniversary model. It appears only one version was made. Here's a link to one that sold at auction for $477.