A conversion neck is one that can convert an instrument from one scale length to another with no other modification. A common conversion is 34" to 32". By overhanging the 20th fret, or leaving it off, you can use the stock bridge location on the body, just adjust for intonation. Such a neck will work on any standard bass body. A conversion from 34" to 30" requires overhanging two frets, or losing one or both.
Gargle consistently hits new pages within minutes of me publishing them. It used to take weeks, then days. I figured it would take at least a few hours, but I have WordPress automatically submitting everything to Gargle, and they are responding in just minutes. I know because my Gargle watchdog tells me. They must have a hell of a lot of hardware working on this. Or maybe I am really special to them.