I ordered a new Speedo cause my old one went out ..
so here is the question .. since i want to leave everything original .. i want to mount the new Speedo under the dash .. would you guys get a new Speedo wire or take the one from the original Speedo ?
and on top if i get a new one how much work am i looking to install the hole story
Thanks

Assuming the speedo cable operates off the transmission, there is only one outlet on the tranny, so if you're asking can you leave the old cable there on the tranny and run another one, no.
Just unscrew the old cable from the existing speedo and screw it onto the new one, leaving the other end of the cable attached to the tranny like it is now.

As to how much work it will be, don't know. How involved do you want it to be? I mean, it's pretty simple, not like an engine swap or something.

You will want to make sure though, before you go to all the trouble of buying and installing a new one, that it isn't the speedo cable itself that hasn't self-destructed. Unscrew it from the speedo and hold the end of it where a passenger can see the little square drive cable turning inside the housing. If it isn't turning, it's the cable or the drive gear in the tranny that's fragged.