The drain plug on my lower unit was bonded to the lower unit, I tried an impac tool but the threads stripped then I tried using the screw dricer method but no help there (break-free was also used) now I drilled it out and the gear oil looked fine and I have a replacement SS plug but I can't find a tap for it it looks like a 5/16 x 27 or 28 , or a 3/8x27 or 28, yes real fine threads but most taps dont go 5/16 or 3/8 with a 27 or 28 pitch. Does anyone know the correct size of this plug? before I special order a tap. It's not metric correct?
