There is often discussion of the relationships among the various Victor TT series turntables, the 101, 81, and 71. The page in Vintage Knob cited by Chakster if you click on the blue Victor in his post, clarifies the differences nicely.
"The
TT-81 is a 101 sans
Double Bi-Directional Servo and with a simplified pitch control system/display ; the functions and features are nevertheless the same : +/- servo, ±6Hz of 440Hz without switching off quartz-lock switch, soft-touch transport keys and electronic braking with reverse-current circuit.
The strobe is included in the servo loop to avoid AC fluctuations from affecting the actual reading.
The
TT-71 is an 81 without +/- servo, no pitch control, an even simplified stroboscope circuit and a solenoid-activated braking pad.
Many integrated players were based on these two drives :
QL-10 (TT-81),
QL-7 (TT-81) or
QL-F6 (TT-81 but with Double Bi-Directional Servo added) among others."
However, I can attest that at least one small point in the VK passage is not correct. The QL10 incorporates a TT101, not a TT81, along with a plinth and a UA 7XXX series tonearm. That's how I bought my TT101, as part of a QL10 ensemble.