Over at Jim Carters site, he has a tech article with pictures showing the fitting and pin locations. Our tech tips on this site has a link to it, but it doesn't seem to be working. Try this
www.oldchevytrucks.com/cgi/htmlos.exe/00448.2.7628682821100030716

The fitting sizes on the US 261's are 1/2" NPT.


I.I. #3174