Kelly, there are two major variations in the 1937 Luger; those with rust blue and straw parts and those with hot dip blue parts.
Then within the first variation there are two sub variations; those with a Mauser Hump and those without the hump. All of these will have a Waffenamt Marks of DE/63 and DE/63.
Within the second variation, there are also two subvariations; those marked DE/63 and DE/63 and those marked SE/63 and SE/63. Further within this second variation there is a transition between the two subvariations; marked DE/63 and SE/63.
You have this transition variation. I don't know how many of these were built, but I don't think too many.
Hope this helps explain!!