So 45586 does work! I honestly thought there was no way it was going to fit even when trying to put the check in the right direction by folding it in half. And being that I have an oddball tube figured even more so it wouldn't work. If I just folded sooner the thread would have been done at page 2.
I bought the flapper again, folded it with some tape, and it slid right in.
As good times said, the picture from the other thread the orientation is correct, notched part of flapper faces up with the rib.... I'll wait for a quality control confirmation before I set the last 2 rivits, lol
Thanks everyone for the help, this forum is extremely helpful. Now I can concentrate on mounting the engine.
