Snap Measurements for '29 Phaeton/Roadster

[Thearne3]

I'm resurrecting this topic because my research turned up two answers from the forum: One posted originally by Tom Weserberg ca 2011 and one posted by Brent more recently. Both good sources! I've attached both for clarity. Note that my questions below are only in reference to the snap holes.

Frame width: Brent shows 43" and Tom shows 42 3/4". Oddly, my new frame is 42 7/8" from Mike's. What is common to both pictures is that the first holes from either side are about 1 1/2" in and the 2nd and 3rd holes from the passenger side are each 10" and 20" from the initial hole, resp. In both cases the wiper center (with or without a hole) is 11 1/2" (!0"+1.5") from the driver side edge.

Put another way, the 5 main measurements (four 'main' holes and center of wiper) are exactly 10" apart and centered as a group on the frame.

The principal difference between the two pictures is the gap between the snaps surrounding the wiper center: for Tom the gap is 5" (leaving 7 1/2" to each of the nearest snap holes), and for Brent, it's 2 1/2" (leaving 8 3/4" to each of the nearest snap holes).

Two questions:
(1) What is the 'right' gap between the snaps surrounding the wiper arm? I would think that you'd want the opening around the wiper post to be as small as possible, ie, closer to Brent's picture, for resistance to water or air leakage around the slot where the wiper post comes through. (Am I correct that for '29 there is no hole: the post comes over the frame?)

(2) Brent shows the snap holes being centered from top to bottom on the frame . However, Tom shows the holes being centered 1/4" (16/64") from the bottom. Since the holes themselves are 19/64" (slightly smaller than the 5/16" snap), this is clearly not possible, since the hole is bigger than the distance from the lower edge. So my question is: are the holes centered from top to bottom, as Brent shows, or should the holes be lowered from center and if so, by how much?

Thanks for any advice or insights!
Tom