No. Not the original SubTank. The rba fits the mini or the Plus.
The original RBA won't fit the mini or the plus, but it should work fine the other way around, shouldn't it?
With the original, you had to switch out the top cap to use the RBA since the chimney hole is (slimmer? fatter?) not the same size as it is on the prefab coils.
On the newer ones, the RBA fits the same profile as the prefabs, so you don't have to switch out the top cap. So to use the new RBA in the old original, just use the original chimney, the one that fits the stock coils, and just don't switch it out for the other one.
The stock coils fit the original Subtank. The stock coils also fit in the new Subtanks. The new RBA fits where the stock coils fit. If a=x and b=x and c=b, then...