Yes, the details you provided are sufficient to order a replacement roller shade for your Grand Design 2670MK RV. Based on your measurements—26 1/8" gear-to-gear width, 0.75" tube diameter, 1" aluminum mounting plate, and a window size of 25" wide by 26" high—the best option is a custom roller shade. We recommend the Irvine Custom Shades - Valu-Line Night Roller Shade, which can be ordered to your exact dimensions and is compatible with Grand Design RVs. When ordering, select the width closest to 26 1/8" (rounding as needed), a height of 26", and the black color. Include your specific details in the order notes for the best fit. This shade mounts with clips on top in the valance, matching your existing setup. For an exact OEM match, you may also provide a photo of your sticker. This option provides a durable and precise replacement for your RV window shade.