When I first moved to the Bay Area in the early 70’s, Fremont was a complete backwater, that house couldn’t have been $20K.
I live in the Mission District. My house was built in 1960. However, about 30 percent of the houses in the area were rubbed out and replaced with 4000 sq foot houses on postage stamp lots and go for 2 to 3 million. I bought my first house in Milpitas in 84 for 100K so I would GUESS 35k to 50k would have been the going rate here during mid 80s. 20k for my house 1960 would make sense though. I bought my house which was remodeled in 1990 to 3000 SQ ft for 400k in 96 when the market was still recovering from the 90 crash.