Transmission guys: speedometer question

I have a chevy 350 trans and the speedo quit working. I figured out that the gear on the tailshaft had moved. I took off the back of the trans housing and can move the gear back and forth on the shaft. My question is is there supposed to be something that holds that gear in place? I moved it back and put it together and it worked fine for a while then quit again. Im figuring it moved back again. Any info would be appreciated.
Thanks

 

http://www.tciauto.com/products/components/speedometer_gears.asp

theres a clip that holds it, half way down the page on the link.
Id be looking for the missing one in there if I was you though

 

Thanks 31Vicky

 

It sounds like I might have a similar problem. The link that is listed comes back with a "page not found" error, although it is on the TCI web site.
I tried searching the site, but could not find the answer.
Could someone supply another link or cut and paste the part about this possible missing clip?

thanks

 

The clip is under the green gear. Hang on a sec for another pic of the clip.

 

google is your friend.

 

Awesome! Thanks F&J

 

GM dealers have them like a $1.50 a piece!