Just purchased the Ryobi RY15523 straight shaft trimmer Expand-it attachment.

http://www.ereplacementparts.com/ryo...33_168451.html

See item 10 and 17 .
I'd like to attach my old gator 3 metal blade trimmer part. The bolt for that attachment that turns on to this stringhead adapter is not the same as for my old curved shaft adapter. The new nut stringhead adapter part is:

http://www.ereplacementparts.com/str...-p-388056.html

Does someone know the thread size and pitch for the bolt that would fit this new adapter (678019002)? It would be the same bolt found inside the stock red bump cap that comes with the new straight shaft trimmer.

Thanks,
Chris