I NEED GEAR SHIFT KNOB FOR 1992 BUICK PARK AVENUE

put transmission shifter in D2 drive it so you feel the second gear on. then stop the car did he down shift .

Yep need to know weather it is drum brakes or disc brakes.

You need to have it rebuilt
or install what is called a CERTA (reman)

check your gear selector switch. the switch is mounted on the transmission where the shift cable attaches and looks like the picture below. Backprobe the connector terminal with the light green wire using a 12 volt test light. Connect the test light clip to engine ground and poke the light tip into the back of the connector at the light green wire. With the key on (engine off) and the transmission in reverse, the test light should come on. If not, replace the switch. If you have more questions, please let me know.

It probably did not slip before the fluid was changed I so the clutches are worn out and need to be replaced The worn fibers were still in the old fluid causing the fluid to be thicker filling the voids much better to shift. Now once drained and new fluid installed it slips

how about your wires could have weak spark delivery, when was the last time you changed cap, rotor and wires .sounds like bad wire symptoms to me.

Your car probably won't go into overdrive below 35 or 40mph.I have a 1993 and I only put it in third gear only when I want it to stay out of overdrive,I always put the shifter in 4Th or overdrive.If your trans jumps hard between overdrive and 3rd gear or is always searching for a gear to be in you should be concerned and have it serviced.18 gallon tank.

The motor,and ,or, the transmission mounts are broken,allowing the shift cable to move.

one of the wires on coil pack is wrong..

if you can place it in any gear and it will not move, first check fluid level and condition of trans fluid, if it smells burnt you may have to replace tranny