[rockyrivermark]

1970 c10
350/350 auto
3:07 rear end I believe
New downshift cable installed last year.
Adjusted to full cable pull at wot
Truck downshifts fine under 25.
Also downshifts fine over 45.
Question is
It won't downshift at all between
30-45. Is this normal?
Any way to adjust? Maybe by adding an adjusting vacuum module?
Thanks for any info offered
Mark