Aww. ❤️
But, hmm. As far as the icon goes I just forgot that. It's a separate texture file, which you can similarly figure out by checking the defaulticon column in baseitems.2da. The texture will be i + the defaulticon string + _0 + the texture variation, for example ia_class4_001 for the first light armor. These textures are in swpc_tex_gui.erf instead of the other ones. For the model, I'm not sure what you mean. You can't replace the model for just one item with a simple file swap. If you want to do that, you'd have to make a new line in baseitems.2da and then change the base item type in the .uti file, and even then you are still limited to one of the ten player models (A through J). So you could change the Republic mod armor from D to A-C or E-J, but you couldn't for example make it look like the Republic soldier armor without changing all other D models, because there are a limited number of available slots in appearance.2da. The only practical way to get around this is via a disguise item, like the Sith uniform, Sand People clothing, and Mandalorian assault armor.
If you did want to replace all the D models, assuming you have your replacement models PFBC and PMBD already done, you'd have to install the .mdl and .mdx files for those, and replace every texture variation for every item on that model, of which there are 8 in K1. And that certainly can be done, but it isn't practical if you only want to change one item.