I have seen some VERY studdish yearlings and 2yos before, it's definitely not outside the realm of possibility. Shoot, at the last show I took my yearling to, the other colt in the class was so bad that everyone had to clear the ingate of fillies before he could even be led out of the ring. I kind of couldn't believe they've kept it a colt, if he's already that bad as a yearling. Mine has been slow to drop too, although he's always had the one testicle. The other finally dropped when he was about a year, but the inguinal ring was still quite open and there was a lot of communication, so we opted to wait until this winter (once the flies are gone) to geld him, in the hope that it tightens up a bit more. Mine is currently 18 months and 15.2h. Not studdish either, although I definitely DO NOT turn him out with or next to mares. My vet said that whatever they've got by 18 months to 2 years is usually all you're gonna get, due to the inguinal ring/size of testicles/testosterone. If you've got NOTHING so far, I dunno that you're gonna get them to drop on their own.