This may be a really dumb question.... I recently changed the knock sensor on the sbc 350 in my jeep to relocate it since the new headers I installed would hit the sensor located on the passenger side... I removed a bolt/plug on the driver's side and put the knock sensor in that spot and alleviated the problem with the knock sensor. So here is the issue I am having. I had read somewhere that the engine block had drain plugs for coolant and was thinking of draining it to put in new coolant and avoid the coolant that seems to get left over in the block from mixing with the new clean fluid. All the info I am finding points to those two plugs, the one I used to put the knock sensor and the one I removed the knock sensor from. They are located about the middle of the block right above the oil pan. When I removed the knock sensor and relocated it to the opposite side, there was no fluid coming out of those to holes... Is there really a coolant drain plug in the block?