Tektronix BNC term feedthu are fine, vintage US made are usually OK
Not all Tektronix BNC feedthrough terminations are the same. The larger 5 watt ones were manufactured by someone else and Tektronix just put their name on them; I have one marked Tektronix and one marked Probe Masters.
011-0049-01 <1.1 DC to 250 MHz and <1.2 DC to 500 MHz 2? Watts (small white one)
011-0099-00 <1.1 DC to 100 MHz 5 Watts (long black anodized body with fins)
I also have a commonly available square plastic cased "1 GHz" feedthrough terminator which gets remarked by companies like Rigol. When tested on my 300 MHz oscilloscope, all of the above perform practically identically, and the same as the internal switched termination.