T-5 speed-o gear help

Which clip are you taling about? There's the one that holds the speedo gear onto the cable end and another forked clip that holds the cable in the tailhousing. This later clip is held in place with a 1/4" bolt. The clip on the cable end in the transmission snaps in place thru the speedo gear.(refered to as the "driven gear") The gear(drive gear) on the tailshaft is held in place with a C-clip on the shaft.

I think he's talking about the clip that holds the driving gear onto to the output shaft (the one that drives the speed cable, not the driven one that's attached to it).

I had the same clip fall off on my T-5 not long after putting it in, causing the speedo to abruptly stop working - never identified a cause, but I dropped the tail housing (I don't think you have to pull the tranny to do this), reinstalled a new clip and it worked fine, right up until the transmission met its demise behind a hard 2-3 shift.

Try taking it apart again and installing a new clip. Make sure it's fully seated and installed correctly.

Damn I thought the T-5 gear was held in place like a Toploader. I guess not. The Toploaders (and all similar year's Ford manual transmisions) gear is held in place with a C clip behind the gear. There's a ball bearing pressed into the shaft to insure the gear (the gear has a groove on the inside that meshes with this bearing)moves with the shaft.