I have a few questions on AN hoses and more specifically fittings and sizes.
I would like to add AN to NPT fittings to my BT CC and add -8 hose to the Intake of my 6.1. I've already verified from BT that the NPT size to the CC is 3/8. So I will run -8 hose from the CC to the Intake and to the PCV valve.
My question is, has anyone done this and if so what size is the NPT thread size into the Intake Manifold just behind the TB opening and the Oil filler breather hose L adapter hole. It looks like a 1/4" NPT with a -8 hose will suffice for both but wanted to make sure.

I'm also looking to do the Moroso coolant tank overflow hose with a similar setup. It looks like a 1/8 NPT on the cap collar and 1/4 on the tank itself with a -6 hose. Any help would be appreciated.

AN is a type of fitting not a hose size. IIRC the thread pitch of AN fittings are British Standard.

Examples
A -8 AN fitting is spec'ed for use with 1/2" ID hose.

A 3/8" ID hose is spec'ed for use with a -6 AN fitting.

AN sizes
-2 = 1/8
-3 =3/16
-4 = 1/4
-6 = 3/8
-8 = 1/2
-10 = 5/8
-12 = 3/4
-16 = 1
-20 = 1 1/14
ect.

In other words, every " - " is equal to 0.0625 or 1/16 of an inch.

- - -

I highly doubt the intake manifold uses anything with an NPT thread pitch. If it's actually a pipe thread pitch, odds are it's a fine M pitch (metric).

AN is a type of fitting not a hose size. IIRC the thread pitch of AN fittings are British Standard.

Examples
A -8 AN fitting is spec'ed for use with 1/2" ID hose.

A 3/8" ID hose is spec'ed for use with a -6 AN fitting.

AN sizes
-2 = 1/8
-3 =3/16
-4 = 1/4
-6 = 3/8
-8 = 1/2
-10 = 5/8
-12 = 3/4
-16 = 1
-20 = 1 1/14
ect.

In other words, every " - " is equal to 0.0625 or 1/16 of an inch.

- - -

I highly doubt the intake manifold uses anything with an NPT thread pitch. If it's actually a pipe thread pitch, odds are it's a fine M pitch (metric).

Thanks for the info. I totally understand about the AN and the - designation. The reason for me asking is that my plans are to tap the holes on the Intake to NPT sizes to accommodate a AN adapter and use AN fittings and hoses to replace the standard heater hose setup. I know the fittings on a stock Intake are press-fit, I was just wondering what that hole size was and whether a 1/4 NPT fitting is large enough for the existing holes before I go yanking that pressed fitting out.

NPT is national pipe thread and it is not metric what you need is a NPT to A/N (army/navy) adapter commonly available at most speed shops as well as summit and jegs. In this case you want a 3/8" NPT to -8 A/N Fitting
Plenty of people have done this its just a lot of work to do it right.