Yes. There are threads. The stock location for the knock sensor is low on the 2nd cylinder. On my 90 6-bolt block, there were threads in the non-stock spot closer to the head on the back of the 3rd cylinder, but not in the stock location. I just used the non-stock 3rd cylinder location. No problems. Reads knock just fine.

On my 93 7-bolt block, 3 holes (the stock and 2 non-stock knock sensor locations) were threaded. Beats the **** out of me why, but there were 3 holes and all were threaded and could potentially be used to hold the knock sensor.