My k plane thru hull fittings just have what appears to be a female thread of unknown size/count. What type of male fiiting is suppose to go into the thru hull fitting and ram. I have looked at other k planes and they appear to use what looks like a tube with a flare fitting, but i just have standard threads on the inside of it. Nothing for a flare fitting to make a seal against. I have searched for hours trying to find what I need for inside and outside of the transom for the k planes, any input would be appreciated. thanks.

(I think)standard inverted flare, I think 1/4". You probably cannot see the flare portion recessed into the fittings. I just finished a restoration where I tried to shorten the lines to clean up the bilge and no one could do the 3/16's fittings on my lines (hoses are 3/16") so I used standard steel, automotive transmission lines. Worked like a *****.

My k-plane fittings were 3/16" inverted flare, both inside and out.

I too just used brake hardline for the lines. Worked out pretty good.