. . . I figured if getting airbound was a hugh deal the stat manufacturers would drill it when they build it. . . .
When I bought my first 261 in 1971 (a 1960 engine out of a large school bus), the thermostat had a hole in it and the replacement thermostat (from NAPA) also had a hole in it. The 261 thermostat and housing (and water pump) was significantly different from those items on a 235.
