oil level sensor
 

My oil level sensor leaks from the pan. I want to take it out and replace it with a bolt. What size bolt do I have to use? Thanks
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'91 LX 5.0 convertible, T-5, ported/polished/milled .030 E7 heads, 1.94/1.60 valves, 1.6rr, March Performance Pulleys and A/C Eliminator kit, short belt, K&N panel, electric fans, glasspacks w/dumps, Centerforce Dual Friction, FMS adjustable cable w/quadrant