Sony TC-755
Sony TC-755A
Sony TC-756
Sony TC-756-2
Sony TC-758
(june 1973 ... 1980)

Pioneer's first business was loudspeakers - Sony's was tape recording.

And the sales showed that fact, especially with the 75x series : there are oodles of them around the world, thousands and thousands and thousands : from the original TC-755 to the auto-reverse TC-758 by way of the 2-Track TC-756-2, Sony was trusted by many.

In fact Sony was trusted by most when it came to recording at large: whether reel-to-reel (professional & consumer), cassette (bis), video (U-Matic, Betamax, Hi8, Betacam, DigiBeta), DAT (pro and consumer), professional 48-Tracks DASH and the APR-5000 masterpieces... a lot of the 20th century's sounds were kept on tape by way of Sony.

All versions are stacking F&F heads but only the 756 and 756-2 travel to 38cm/s.

Better than any of these was the TC-880-2 (aka TC-8750-2 in Japan) but the price of it was... on par with its quality. Better, too, were the TC-765 and TC-765-2 (aka TC-R6 and TC-R7-2 in Japan) but those came at the end of the decade.
For the 1970s, Sony sold more RtR decks than any other manufacturer. It was a good period for Sony, arguably the best.

In true Sony tradition, RtR decks had different names in Japan - below are the equivalences.
Besides the 7760, I know of two more (very rare) versions but haven't found enough details so far to bring them online.

TC-755 = TC-7650
TC-755A = TC-7660
TC-756 = TC-7750
TC-756-2 = TC-7750-2
TC-??? = TC-7760
TC-758 = TC-7960

The TC-755A was also available in Germany as a WEGA B 4610.