Transmission shifting problem

have a transmission shop test drive it.

This vibration or shudder is caused by a clutch slipping. When you mash the pedal it puts max PSI ad it seats the clutch.

The true way to repair this is to rebuild the transmission and replace the clutches and seals. If you want to verify which clutch it is, I attached all the needed testing info.

Let me know what questions you have and we can go from there.

Have a 1998 Ford 350 van with 147,987 miles on it. This van is used mainly to move travel trailers around on base(work with Outdoor recreation on a military base). Feels like something is wrong with the gear shifter as it will not go into park any more and also when we start the van we have to put it in neutral and then turn the key(it's an automatic).

could be a shift safety interlock problem.

I've fixed a couple of this vintage van in the last year with identical sounding problem. Both times it was a loose bolt attaching a link to the back end of the shift arm. Have to pull the lower dash cover and drop the steering column (4 bolts) to get to the offending fastener, but in both my repairs it was only about a half hour job and problem resolved.

Great info. I think you are referring to the transmission range selector lever. I attached the procedure for this.

Please let us know if there is something else we could help with. Thanks