I know that hminky is eventually going to look into upgrading David Drake's stuff and may have already created some stuff that may be suitable.
As for 50's logging trucks etc.
These are on the DLS
<kuid:546049:2107> v1_kamaz_les1
<kuid:546049:2108> v1_kamaz_les2
<kuid:546049:2090> v1_kraz2
<kuid:546049:1098> v1_kr18
<kuid:546049:2127> v1_maz_7_les1 t agach
<kuid2:73394:25434:2> SWE SCANIA LS111 Logging Truck Green Black
<kuid2:73394:25435:2> SWE SCANIA LS111 Logging Truck Green Black Loaded
and may pass for 1950-60 era
and there are these which appear to be 40's era
<kuid:506034:479346> JR old Mack truck black (no trailer)
<kuid:506034:479344> JR old Mack truck black (w/trailer)
<kuid:506034:479349> JR old Mack truck black emty (w/trailer)
<kuid:506034:479347> JR old Mack truck red (no trailer)
<kuid:506034:479345> JR old Mack truck red (w/trailer)
<kuid:506034:756737> JR car trailer logger
<kuid:506034:756738> JR car trailer logger empty
While payware now JR has a history of migrating older scenery assets to freeware over time.
Edit: here is what hminky has uploaded so far, pines on the left, spruce on the right, and the sole fir in the center. (they definitely look better than what you have shown above.)
Tane Sp3
More to come as Harold finds time.