Emma S, my avatar is a "Judy" mystery. I'd never done one before and this one got me hooked on her mysteries. There are no "y" seams! The thread is called "Welcome Aboard the Mystery Train" and it was begun on 2-12-12. See posts #1, 82 & 83, 312 & 313, 663, 681, 1003, and 1270. Sounds like a lot, and I can't really remember if you need all of them or not.
Saving my sewing energy while waiting for the new train. :-)