Goldstar TSR-680 and TSR-681

This must be one of the rarest Goldstars. I had never seen it before until today. It measures 54cm x 30cm x 13cm. It looks like it shares the same chassis and controls as the TSR-580 and 581. But the front is totally different, with nice big analog VU meters. It also has "ASAP" song search that can skip forward or backward 3 tracks. I really like the large font they used on the tuner dial. I am not sure what the difference is between the 680 and 681, but I think one has black knobs and switches, while the other has chrome.