Most likely, it's the noise resonating along the driveshaft from slop in the rear end gear, u-joints or trans output shaft.
replace the vacuum shift diaphragm lacated on the side of tranny make sure vacuum hose has no leaks or cracks in it or just replace it w/ good non collapsable vacuum hose
When was the lasttime you checked your tranny fluid? You might have fried your tranny.
Makes the tranny shift at higher rpms when activated.
Can be worn out synchronizing rings.
a vacum works with the tranny to Shift an automatic vehicle
Inside tranny
i had same problem. what i did is replca the tranny filter and tranny oil, and solve my problem try it. i had same problem. what i did is replca the tranny filter and tranny oil, and solve my problem try it.email me see how you doin -rockandroland117@yahoo.caANSWE ANSWER= shift lockout. some times wheel sensors will go out and the shift lockout will occur to prevent further damage to tranny.
Check your transmission shift solenoids
inside the tranny pan
The tranny slipping
Your band, 1-2, 2-3, and 3-4 shift solenoids are located on the tranny. You have to drain your tranny fluid, remove the pan, and they will be located in the valve body.
the gear shift might just go inside the tranny and shift the gears internally.