FYI, I used the longer gear from my C-4 in my T-5 and had issues. When the cable housing was tightened down the longer nose caused the cable gear to hit the tranny housing (internally). It actually rotated with resistance going forward, but when I backed up... the cable gear held (from the friction on the nose) and caused the tailshaft gear to "walk" backwards..., out of mesh.
I tried for hours to get the tailshaft gear forward, but there is a spring clip that I could not get enough pressure on, even with a screwdriver. As a last resort I found that the thin tubes for an old, stand style, halogen torch light (see image) I had "just" fit over the tailshaft, but wasn't too thick to snag on the seal. A tap with a rubber hammer put the gear back in place.
But, as has been noted the gears often need to be changed. And, for me, eventually I will have to pull the tailshaft and replace that gear. In the mean time I used a GPS to get equivilent speeds that I have printed out and taped to my dash.
Tom