Today I bought a 1 5/8" steele freeze plug. Being under the motor mount I could not install properly so I had to use a rubber plug. 1 1/4- 1 5/8". I ran my motor with water and flushed out the radiator several times. Tomorrow I hope to get some anti freeze, coolant and some oil and a filter and I'll feel better about my motor. Thanks Guys you are always a big help.