John,
The model number for the first Sears Direct Drive washer is 110.81061100. That's a 1980 model number. It is a 60-series machine. This washer used the agitator with the built-in filter, which was WP's replacement part number 62964. A follow-on '81 model that also used it was 110.81161100.
There was a basket mount filter model which used a similar agitator without a filter, part number 63018, on models 110.81167x10 and x20, where x is the color digit.
Interestingly, a third model, 110.81177800 shows in Whirlpool's book, but not on Sears' site, and the 110.81167x00 is in the WP book, but all blank and not on the Sears site either. Its like these models had been conceived, then replaced before they were even marketed.
But, the three models above used the funky gold agitators, and one was definitely a 1980 number. They may not have existed until 1981 in production though... The catalog has a caption for these two agitators "Direct Drive rear motor models".
Gordon