When I try to shove the speedo cable in the tranny hole, it seems like it wont go down all the way or something. When I put the pin around it (dunno if Im putting the pin on right) the cable will come back out with a lil tug. Anyone had the problem before?

 

Try this, it might help
Put the horseshoe clip in the slit
Pull some of the speedo cable out of the sheath and insert it in the hole making sure to align the keyway
Then push the sheath in and hopefully it will lock

good luck