ST-5000
(may 1967 - 1968)
ST-5000F
(february 1969 - 1976)

Part of Sony's first foray into HIGH-Fidelity and the last original ES unit to appear after the TA-1120, TA-4300, TTS-3000 etc. Yes: ES dates as far back as 1965 !

The original ST-5000 was quickly replaced by the 5000F (F for FET), the latter vanishing also quickly in favor of more affordable units with less drastic bulid quality.
Just as for the TA-2000F, an xxxxxx-rare black version of the 5000F has resurfaced in Germany ; since both units appeared in the same country, I suspect these black versions to have been "distributor" or even "shop" custom-made. That said, a black-faced STR-6060F has been discovered in Japan (STR-6000) so... maybe... perhaps...?

Like a few other 1960s units, the 5000F remained available in Japan far longer than elsewhere, even remaining more expensive than the excellent ST-5950 topper in 1976 !

A very informative review of both models is available at the Tuner Information Center.