For about 95% of FMJ cars, there are 5 different ends to the speedometer cables.
There are two different styles of plastic ends that attach to speedometer head. Yours should have the typical plastic clip on that has been used from ’68 until electric speedometers.
Some early F & M-bodies have this end to speedometer head. They use a metal clip to keep cable in place. This end is made in black and in white.
If you have cruise control, there will be a nut going to the cruse servo, which I “think” a ¾” end wrench will fit.
If you have the plastic speedometer gear housing, you will have this end. The only way to remove cable is to remove the entire speedometer gear housing, and remove clips after removal. I do not care much for this design and recommend to replace with the metal housing design (below) when possible.
This is the older style speedometer gear housing (all metal). It makes servicing the cable, the transmission and a lot of other repairs a lot easier (and less messy). There is also a lot more part availability for replacement gears, as well. I “think” a 1” end wrench (or channellocks, or whatever you have handy) will remove the nut.
The factory nuts are Hex.
The newer aftermarket ones have round nuts.
I would rather work with a round nut cable than I would a clip on plastic housing cable, on any day.
I “think” the cable length is roughly 65” if without cruise. Both cables combined are 80” with cruise - again, going by memory.
Dodge vans , 4*4 pickups, taxi cabs and front wheel drive are different – but pretty much all Chrysler speedometer cable lengths made from 1968 to early ‘90’s are the same within the two types (with or without cruise control).
Now the cars (all pickups/vans all used the screw on metal speedometer gear housing) slowly went to the plastic speedometer cable housing startin in ’75 – but many ’76, ’77, ’78 and some ’79 cars were made with metal speedometer gear housings, because of plastic part availability (shortages).
Now if you are talking about the flexible cable inside of the speedometer cable – then I can’t be of much help to you (I avoiding messing with the flexible cable all together).
BudW