If by "dog rings" you mean synchronizer rings, I bought mine from 1stVWparts.com. Here's the parts list from when I completely rebuilt my tranny and installed a Peloquin. http://users.wowway.com/~clmoore3rd/020_Trans_Rebuild_Parts_List.pdf
I've heard that people just use the same syncro ring for all gears, so I'm not sure why the factory 1st gear syncro ring is different than the others, why it's missing 3 teeth. Getting the part numbers if often half the battle, so with the part numbers listed above you can hunt around the internet to see who carries those items if you don't want to get the parts directly from 1stVWparts.com.
