I have a 83 T/A 305 LG4 auto(700r4). my Speedo seems to work when it wants, e.g. it will work for a few days or maybe a week, then it will not work for a while and so on, also the needle wobbles at about 10mph and under.
I have done a search and think that maybe the cable is a bit seized and needs to be lubed.
I assume the cable is not broken as it sometimes works.
could it be a problem with the head? maybe a stripped gear causing the intermittent problem?

thank you.

 

The low-speed wobble indicates a cable problem. Needing lube is a common cause, a kinked cable housing another. Do you have cruise control?

 

yes, i do have cruise control. could part of the cruise system be to blame?

 

The cable goes to the cruise governor first, then to the speedometer. So, yes, it could very definately be a contributor.

 

my cruise control seized, causing the speedo cable to barely move, getting a weak, intermittent speedo, until the driven gear in the trans rounded itself to nothing. After replacing it twice, I removed the CC, and bypassed it with a normal 1 piece longer cable.

An easy check, unbolt your drive gear from the trans, should be 2 10mm headed bolts I think. (maybe just one...?)
and pull out the gear. If it's rounded, then you have the same problem as me. If it's ok, then plug it back in, and undo the cables at the CC module, and dump lube into the cables and re-try it.