The ‘C’ suffix indicated the Thorens models which were sold with Thorens tonearms, while ‘B’ indicated the ones which sold without tonearms, so TD-160C, TD-160 IIC etc included the latest Thorens tonearm of the time.
There were several different models of the TD-160, but the first was (allegedly) released in 1972, according to the Analog Department
http://www.theanalogdept.com/thorens_data.htm . There were 2 different basic models up to the mid-1980’s (1: allegedly produced 1972-76, II: produced 1976-84) corresponding with variants of the TP-16 tonearm, as well as a TD-160 Super (1982, but see below), which had various modifications including a heavier platter, plinth, mat, bottom cover, and damping materials applied to the motor and other parts.
However, some of the dates may be slightly wrong – they give 1982 as the first date of the TD-160 Super, but I’ve got a review of the Super which appeared in a 1980 electronics magazine (ETI UK edition, October 80), complete with a photo clearly showing the name TD-160 Super, so they are certainly wrong about that, unless it was just a prototype that was being reviewed. However, the review text seems to say it had been released for sale to UK customers in 1980!
So take the release dates as approximate (±2 years).
There were also variants like the TD-145 (1975), which was a TD-160 plus auto-stop and tonearm lift, and the TD-147 (1982), which was an auto-lift version of the TD-160 Super. Finally there were the TD-160S IV (1987-88) and TD-160S V (1988-90’s), which were auto-lift versions based on the TD-147. A very different TD-160HD was released in the 2000’s.