Marlin 1894 factory Lyman receiver sight?

[de1216]

I recently picked up an excellent condition 1894 44 Magnum (1978 made). It has a Lyman receiver mounted rear and a filler in place of the std barrel mounted buckhorn base. The entire gun looks in such great condition that I suspect it's not been altered since new, including NO sling hardware added. But I have not yet found any reference stating Marlin ever made them at the factory like this.
Thoughts anyone?

D

[alukban]

I would think that it wasn't a factory option but I would really like to just see pics