Heater Hose Fitting

I need to pick up a new heater hose fitting (The heater hose nipple at the manifold) I'm not sure what size I need to get. I believe it to be 5/8" hose fitting w/ 3/8" NPT thread, but there are 2 styles, one that is slotted to tighten w/ a screwdriver, and one that has a hex lug on it. I don't have my car nearby, so I was wondering if anyone could let me know what I need to pick up.

I'm not sure that is the correct size either, so any info anyone has in that regard is appreciated.

Thanks,
Jerry