The first stages will have a badge on them. None will be a Delta.
Seconds it will be on the faceplate and they were the only thing that was actually designated Delta.
Oceanic made a number of delta designated second stages. First stages had a different designation. CDX5, FDX10, etc.
The CDX5 is one of the best 1sts that Oceanic sold. Sealed diaphragm with decent hose routing for singles and doubles. You can still get service kits for it. I used a pair of them for several years with singles and doubles. No turret so for sidemount find something else.
The Delta second stages are another matter. It depends on what delta it is. There was a delta, delta 2, 3 and 4. Kits are hard to find but they are out there. Oceanic sold out to Huish and they stopped supporting the older ones. The servicing of these is a pain in the ass to me compared to barrel type seconds like HOG and Deep Six. The nylock nut that is used to set the lever height can be finicky and if you go to far, you're not supposed to back it off. They told us when I did my Oceanic reg tech class to use a new one and be more careful.
The biggest issues I saw with them were the covers. They get stiff and disintegrate. I tossed my Delta III/GT3 seconds when I got the chance and used either Sherwood or HOG seconds on the CDX5's until I went all HOG.
Getting them serviced could be tricky. You'll have to find an Oceanic dealer or do them yourself. If they don't need rebuilt and they are cheap enough, you could use them until they die and then throw em away.
If they are Delta 1, or 2s I'd not waste money on them.
Not when you can get adjustable balanced seconds that you can get parts for and service yourself for around a $100 each.
