I almost always forget about this except when I'm driving and it starts squeeling like a banshee. It would often squeel and then go away for a while but today it finally broke. How tough is this to replace on a Ford build? Will upper plenum off be enough disassembly?

 

Did the upper Mazda cable break, or did the adapter cable at the transmission fail? The adapter is located right near the exhaust & can be susceptible to melting (I wrapped my cable in heat sleeve). You can separate the two cables where they join each other & see if you can spin the Mazda end with a cordless drill. If the speedo works & is quiet, check the adapted to see if it failed.

 

Yes, I have my adaptor and part of the cable wrapped too. Just wondering about access at the firewall for the cable. Best bet will be to pull the upper manifold to avoid frustration. Not a lot if room right there.

 

Got my cable and a new upper gasket. Will tackle it this weekend. I have some 1/2" heatshield I was going to put on it, but I need 1" to go over the nut. Can I just slice the headshield and wrap a few spots with foil tape to secure it, or is there a better solution?

 

oK, so for anyone searching for this issue in the future, here's the deal.
Very unlikely you could do this without taking off the upper. Just too tight and crowded back there. The good news is that if you do have replace the cable it will give you a chance to route it up along the tunnel verses how it was stock. I did wrap it with the slit heattube and used heat tape and zip ties to secure it to the cable.
An added side benefit is that I discovered my lower manifold bolts needed some serious retorquing.
Reassembled, test drive, everything works and cable is QUIET! yay

 

This is the stuff that I used on mine: DEI Cool Tube | JEGS High Performance