Consider using BMW tranny plugs for your project. Some versions are
hollow and have a large hex head nut end. You could drill the center of
the hex out and still have the hex available for turning the plug.

http://www.bmwpartsweb.com/Part-Number/Product-Detail__23117527440_GEN_E095124A.aspx

I sometimes use these in Vanagon filler hole locations so I can remove
the plug with a regular wrench.

Mark

Alistair Bell wrote:
> Thanks but I don't actually need one. Or I should say I don't need one now. My interest is more about adaptor to the threaded holes for use in a trans cooling set up.
>
> Alistair
>
>>