Need just the dipstick or the tube or both? Macs or Carpenters should be able to fix you up with a new replacement. You might also see if Mummert has anything listed.
If the engine is apart or the oil pan is off so that the threading debris can be caught, then the dipstick hole can tapped to 1/4" NPT and a universal dipstick installed. Here’s the link to a previous thread showing this. I use the Canton universal dipsticks on a majority of Y rebuilds for both front and rear sump oil pans.
http://forums.y-blocksforever.com/FindPost76444.aspx