Fuel Filter Head In/Out Thread Sizes

I'm doing a little plumbing under the hood and I'm trying to find out what size/thread the fuel in/out fittings are on the spin on filter head.

Also the fittings on the filter on the back of the head.

Last time I did this kind of thing was on a 7.3 IDI filter head. After a month of trial and error I finally asked on a forum and was informed by EVERYBODY that it was a proprietary fitting that I has to get from International.

It was one of those things that everybody just knew. Except me. :(

So this time I thought I'd forego the month of trial and error and just ask right away. ;)Attachment 6711Attachment 6711

I am pretty sure they are NPT fittings.
I have never come across any propriety fittings on a GM yet

It's been quite a few years since I've messed with one of those filter assemblies, but if I recall correctly, they are flared fittings (like brake lines), and one size is larger than the other. Sorry, I'm not much more help than that.

Casey