Trip out to Warrenton to clinch the OR 104-US 101 portion of ORH 105 indicates that it's now OR 105, despite lack of shields.
Caught the bridge inventory tag over the Skipanon River which reade RTE: 105, though I missed the HWY: value; and GMSV isn't focused enough on to make it out.
OSM has it mapped as OR 105, with an OR 105S nearby.
I will verify with the ODOT GIS to see if it's intended to be a Route and thus included in the set, noting the special circumstances of the non-signed post-2002 Routes. (I'll also double check what it says about 182 before I have it pulled from the browser, even though it's inevitable per the Lincoln County minutes).