The 18999 has both oldstyle grips. Barrel has no knurling but has a new type cocking slider, endcap has 'not to be removed' stamped without retainer screw. No box, but according to the former owner all original. So only the cocking slider and the endcap (older one has a retainer screw) deviates from another prewar Senior I own. Serial is in the 9000. Try to upload couple of pics during the week