Yes, the outlet of the solenoid is NPT. Then the barb fitting screwed into it. From there we're 100% barbs..
The threaded port on the solenoid is doped up pretty good with white pipe dope. It looks removable, but I don't know how much torque I'll need to do it and whether adjacent material will handle said umph. I have a baggie of brass fittings and tubes that came with it. I didn't put this unit together. I bought it from a guy off craigslist when he got out of planted tanks, so for me there is a bit of mystery purely because I didn't go through the steps of assembling it myself. So far it's worked well, I'm just not liking the look. It's functional as is...just ugly ;-)
I would give it a go to see if you can remove the threaded port on the solenoid. I would try to put the entire contraption into a good bench vise, and then try to torque it off with an appropriate sized wrench.
I looked at the Parker. Beautiful but more $$ than I can swing right now. I am happy with the stability of the Fabco once it's dialed in. A little touchy at first but stays put once you've got it. The Fabco is $34+ on their store site. Is that a good price or should I shop?
There is a seller on eBay that is selling the Parker H3L brand new, with shipping for about 30 USD. This is less than the Fabco that you are looking at.
Hope this helps,