car been sitting for many years...owner said he flushed it and changed fluid and had to fab up some of the missing kickdown linkage.
car wont shift out of low gear.

any quick way to determine if the kickdown linkage is not adjusted properly or the problem is internal?

Disconnect the linkage at the transmission lever, if it will upshift the problem is in the linkage.

The linkage is probably JAMMED ... all the way back.

thanks...so with kickdown disconnected it should up shift if problem isnt internal or shift linkage.

JUST CHECK ...if the KD lever moves freely with the throttle action.

If the KD is good then plan on pulling the pan unless you are advised to check the 2 band adjustments 1st. Not sure what 2 check next (I'll defer to Kunkel) but inside you'll immed c if the struts are in place & may need 2 pull the VB & do air checks in the case ports w your rubber tipped shop air nozzle

If the governor's weights are sticking, it will not shift either. If you take the tail housing off, the weights should move freely when you rotate the output shaft. If they are stuck, there is no signal to the valve body to shift the transmission. Been there, done that, have the T shirt.
Craig

What Craig said & I think you can check the governor psi at the port back there & not have to open it up (unless it is stuck)

A stuck gov ? ... that is a rare bird ..... uNless you have some severely toasted ATF in there.

I've seen lots of cobbled-together linkages that hold the lever back over half way at idle.

x 2 ....plus some are missing the return spring

and then there's the occasional linkage foul up that wont let the throttle open all the way.