It sure looks like an NAA-built gear to me.
Here's a BT-14 (NA-58) gear for comparison (the NA-64 Yale gear is identical)

Notice the rounded towbar hole and the mounts for the wheel pants at the top.
The only real difference is the two mounting lugs on the forward side (and presumably rear side) of the strut, which I'm assuming was either a mounting for the brake line or another wheel pant mount.
Looking through the Harvard Mk I (NA-49 & -61) Parts Manual, it shows a similar lug on that gear leg (only one though)
Hope this helps.