Case top is not for a Constellation. One would expect a Constellation of this vintage with a steel back to have a steel case with gold capped lugs and gold bezel, not a gold plated case with a steel back. This looks like a NOS case back added to an unknown case top, perhaps a Seamaster as the lug style is more similar to this than a Constellation. Also looks like the medallion is rose gold with a yellow top. The integrity of this watch is highly suspect, dial included.
That looks like one of the Watchco backs that was for sale a few months or so ago, that has been added to, as Norm stated, a non-Connie case. Run away.