Use of any of these can make any scenery asset accept lumber:
PL Lumberyard,<kuid2:30671:27377:2>
PL WoodProducts,<kuid2:30671:27384:1>
LARS IndustRail,<kuid2:69871:10001:3>
ProtoLARS IndustRail,<kuid2:69871:10002:3>
The built-in Pulp Mill accepts wood chips and produces general goods, dunno if that was the one you were thinking of. Multi-industries and non-built-in industries could be made to do whatever combination was desired of course.
There's a flowchart in the manual which shows how the built-in industries and products are inter-related. See this section of the Trainz wikibook for details of where it is and a list of corrections to its minor errors.
No, this one is one DLS somewhere.
Found it. Factory_8_GenGoods KUID:1942:27019
And a snow version. Factory_8_GenGoods_Snow KUID:1942:27029
Here's some others I found searching DLS for "lumber" in description. Lumber Warehouse KUID2:35815:26206:2 BI Lumber Unload Dock KUID2:128094:27003:1 Gunnellinda Mine KUID2:77573:241441:1 Invisi-mill small KUID:96914:31000 ikea_industry2 KUID2:189041:221:2