"VL cams have removable shafts UL cams do not."
Over half of My 9 UL cam sets have removable solid shafts,
That are drilled and pinned with a round head Rivit looking pin opposite the cam lobe on the gear side.
I do also see tubular shafts that are integral to the gear/lobe with plug on end. Or half hole through.
Logic tells Me the early 1937 to 1939 motors used the hollow shafts.
I have 3 sets, One of each year, And I believe they came with the integral cam gear to shaft. I also see the idler gear drilled through on these.