Jon Shiu is 100% correct about the order for the Crown/Speed & Super Graphic where the original back came with a fresnel. They have the correct spacing.

Chamonix made a huge error in manufacture because they hadn't taken the extra thickness of a fresnel into account which shifts the focus plane consequently their first batches of cameras had a focus error mainly only seen when shooting at wider apertures.

Fresnels below the screen are quite common Graflex, Linhof, Wista and many others have all used them this way, current Lihnof models use them on top though.

There are some Graflex backs (usually spring backs) that had no fresnel (from new) the castings are almost identical except the 4 corner pillars which support the ground glass but the OP's clearly not got this back.

Ian