I don't know off hand, but on my 66, the C4 has the cable going in on the drivers side. The toploader, on the other hand, is on the passenger side and a LOT longer. I would think that's the difference with the FMX too.
You can do anything you want to......ONCE!
aka "my 66 coupe"
Nope, I'm almost 100% sure (going from memory, cars not here) that the speedo cable for an FMX is on the passengers side... Either that or I had the car turned around last time I yanked it out, LOL, which is a possibility. I can check for sure soon here.
'72 Mach 1 || '90 Talon TSi AWD
"Thats not a leak, my car's marking its territory!"
"If you've done it, it ain't braggin'." -Roy Rogers
When I swapped to a toploader from an FMX on my 73 (the toploader was a 72 and the fmx was a 73) I was able to use the same cable, although it does not seem exactly right. But it works well so far. It was on the passengers side on both of them.