My FJ was missing the rubber antenna boot when I bought it. Bought this replacement 3 years ago and it’s great. I also replaced the stock antenna with a stubby antenna. Can’t comment on if there is any signal loss cause I only use the aux port but the look is great.
TOYOTA Genuine 86392-35031 Antenna Ornament https://www.amazon.com/dp/B00G0P0GHQ/ref=cm_sw_r_cp_api_glc_fabc_0764FbPD8NZCR?_encoding=UTF8&psc=1
CravenSpeed Stubby Jr Antenna Replacement for the Toyota FJ Cruiser 2007-2014 | 2 inches https://www.amazon.com/dp/B00U82B130/ref=cm_sw_r_cp_api_glc_fabc_f.64FbEXR6AG5?_encoding=UTF8&psc=1