David,
If your oil pump worm is attached to the crankshaft, then indeed it is different from the 1936.
I had a look in the 1938 Spares list (sadly not illustrated), and it seems to collaborate this. Part number 18213 is the oil pump worm; not much can be told from that alone. Part number 18309 is the key for the oil pump worm and generator pinion. In the 1936 arrangement, there is no key required for the oil pump worm. Unfortunately I do not have a copy of the 1936-37 spares list to cross-eliminate the part numbers, but it does seem they made a change. It would seem like a retrograde, as the worm driven by the tang of the crankshaft nut allowed some latitude on the 1936-37 models. With the worm attached to the crankshaft in 1938, the alignment of the outrigger bearing in the timing cover need to be precise. The EW had the worm attached to the end of the crankshaft, but it was simply cantilevered; no outrigger bush.
Anyway, the gutter and oilway serves an identical purpose except that it oils the journal directly. Ya learn something new everyday here on the Forum!
-Doug