So I've had the 13 car for 10 years and have methodically done the gear box with checklists and routines that would drive Dilbert crazy. So today, I'm doing it for the upteenth billion time and everything is looking squeaky and copasetic. The as I put the layshaft stack in, something feels kinda tight and weird, but it goes....somehow. Then I drop the alignment pinion in and it won't go all the way down. Then somehow I get it all the way down but obviously not the way it should go. The stacks spin but not smoothly and I'm pretty sure this will never go back in the box. Hmmmmmm good thing I'm not at the track trying to make the grid in 40 minutes.
Long story short I R&R both stacks 1/2 dozen times til I notice I had somehow swapped the pinion 3rd and 4th.
So there you go, the only April Fools joke I got all day. And I had to do it myself.
Aren't you glad you never do $hit like that? You're welcome.