OH jees, i just did this like 3 months ago. ok im not sure of the size, pull out the stock sensor, and take it down to a racer shop, have them match the threads. ok now listen VERY carefully, the oil preasure, if you tighten it too tight, will strip. ask me how i know. i tightened it just a little to tight, and the sensore came off in my hands. the brass adaptor still in the block. yea, that was fun, i ended up drilling it out, and using a #3 screw extractor. just BE carefull!!!!!