NAV LIGHT MOUNT INSTALLATION

HI,
I am installing the Vans supplied Navigation (Position) Light fibreglass mounting insert on my RV6 wing tips per the instructions supplied by VANS.

On these instructions dimensions A & B are given for the vertical location of this mount, but there is no definition of where points A & B are on the Mount. Also they are quoted as 1 7/8" & 1 15/16" ie 1/16" difference on undefined points that cant probably be located more accurately than + _ 1/8" so that is ridiculous.

If anybody has installed these mounts on their RV wing tips can you please advise what reference points on the mount you used to define points A & B, or are they just not critical (if so then why have 1/16" difference between them?.

Thanks in advance
Graham
New Zealand.

Since posting this I have heard back from Vans. It appears that the 40.5" fore/aft dimension from the Trailing edge is to the aft end of the flat that the light sits on, NOT the aft edge of the mount. The vertical dimension (not surprisingly) is not critical. So my cutout in one wing is too far forward!!!
I would have expected a higher standard of from Vans.