Got some questions for y'all

[Spedy7]

Hey y'all, new here. Just bought myself a '69 C10 from a friend (it's a running project) and new to the GM/Chevy scene (coming from a Ford family, have a '66 Mustang too). Got her running ok after sitting for a few months. Has a 350 and TH350 from something (originally a 6 cylinder truck).

I was trying to figure out why the speedometer isn't working - it all works when rotating it from the transmission side, but driving it, it doesn't work. Can't tell what the drive gear looks like, but the driven gear looks like the right one and isn't stripped or anything.

Also trying to hook up the temp and batt gauges - what wires would you recommend tapping into? Alternator was replaced with a built in voltage regulator too, so the old volt regulator was bypassed.