Phone call with Roger at Zenith. Three topics discussed.
1) Forward Angles (75F12-7) - I discussed with Roger the difference in the plans call out of t=0.025" material and the delivered t=0.032" material. Roger said the new parts are t=0.032" but if the older t=0.025" are installed that is ok. Roger said the increase was likely due to the higher horsepower engines being installed by some builders. (*I have the newer parts on hand so will be taking out the t=0.025" and installing the new parts t=0.032").
2) Four Point Harness System - I explained the rear gusset issue including the plans illustration which incorporates the vertical rivet line and the the new rear gusset which does not. Roger said the new part is a change made in the newer models and is compatible with the BRS Chute system. Using supplied parts is fine or older style. (*I'm electing to fabricate the older design which incorporates the vertical rivet line.)
3) I asked about the rivet spacing on the Mount Channel SD75F30-1, Roger said I should double up on the rivets which will improve the strength and improve looks / symmetry. (* I will double up the rivets which is a win win.)