Speedometer noisy and jumps around,tried another speedometer and greased cable,did not help. Could the spedometer gear in the trans cause this? The cable and housing look good.

Gear wouldn't cause a noisy speedo.

problem is probably in the head unit in the speedo.

you might try to find some one that has a good working unit or a good spare and just try it before you start buying things.
What type and year of car.
I have seen this a lot up here in the snow belt don't know about southern states, but here they just get old and dry. did you put something up into it like WD 40?

I have a 65 New Port but don't know if it works cuz I bought it for parts without a motor.
Surprised some one else hasn't chimed in yet this is kind of a common problem with older mopars. I'm really cheap and when this has happened to me in the past I just disconnect and use a tach to judge speed.
usually if the head unit is good a new cable is in order. Don't go out and buy anything till you hear more. Right?

PB and WD-40 are NOT lubricants. PB is a penetrating oil that will quickly evaporate and WD-40 is a moisture displacer (WD-40 actually stands for water displacement, 40th attempt to get the formula just right) You should try the powdered graphite, or actual light lubricant.

I have used white lithium grease in mine with no problems. A heavy grease, like bearing grease, is NOT what you want. Also, did you just replace the inner cable or the housing too? I have seen housings get melted or pinched and reusing a bad one with a new inner will not help.

I've got the same problem with my '65. Three heads, samo samo. Ordered a new cable and housing. Here's hoping.

New speedo cable fixed that problem for me.