George,
No problem on the year mistake. My guess is that the left-door lock/key option became available in 1952 when the push-button handle was introduced (no need to drill a key-hole in the driver's door).
Observation:
$37.50 for the hydro-vac options was a lot of money.
Paul,
Regarding mounting oil filters on the firewall: the following opinions/speculations/observations are not based on much documentation (so, ignore/disagree as you see fit).
The firewall location for an oil filter was common for COEs.
I'd bet a factory-installed
RPO - factory option 2qt oil filter would have been placed on a manifold (1949 and later), but an
accessory 2qt filter might have been located in any location chosen by the installer (owner, dealer, mechanic, etc).
Here is an installation sheet for a 2-qt filter (late 50s). It would be interesting to see other 2-qt filter installation sheets for 1949 and later filters.
It was much more common for earlier oil filters to be mounted on the firewall
1946-1948 S-2 Series). This "habit" probably persisted into later years by the dealers/mechanics/owners who were used to installing earlier oil filters on the firewall (if the 49 and later filters' hoses were long enough for a firewall installation).
