Maybe I'm wrong, but I thought OPD stands for overfill protection device. It doesn't sound like it would be an issue to use a filled one, but an issue to re-fill it.
The one I have does NOT have the triangular knob that are on the newer tanks with OPD, but has a yellow sticker on it saying it includes an overfill protection device. A local family owned place is willing to fill it up because of that & said that the original OPDs only had the sticker, not the special triangular handle. He also mentioned that I might want to keep bringing it back to him to fill because a lot of the big boys won't fill them if they do NOT have that triangular handle. Double check and see if there is a sticker on it & bring it to a family owned place if it does.
Mine is a yellow somewhat rectangular (it might have rounded corners) sticker just a bit below the nozzle.
As a bonus, this guy has the credentials to recertify an out of date tank & he'll do it at no additional charge if you refill your tank at the same time.