transmission problem
 

I have a 2001 T & C Chrylser LX mini van...the problem I'm having is when the car downshifts to between 25 & 30 mph, I get a thump. I can't say from the transmission because I don't know where it's coming from i.e. the transmission or the drive shafts. I've also been told it could be a "speed" sensor. Any suggestions would be appreciated before I take it to a transmission shop.

Miles?
Maybe you need an oil and filter change on the transmission. It will not do any harm and it is a cheap thing to try first. Get 4 qts of Mopar ATF+4 (don't use any other ATF) and a filter kit and do it yourself or get it done.
Check if the solenoid pack gasket is leaking (very likely for a 2001), if so then you need a new solenoid pack since you cannot get a loose gasket.

transmission problem
 

Ettienne,
Thanks for your suggestions, however, I already had the oil/filter change along with the addition of Lucas. I have approx. 84 K for miles. I've had a leak that the mechanic said was caused by a leaking hose from the transmission but now I'm going to ask them to check the solenoid pack gasket....thanks again for the advice.

Ettienne
I made a mistake on my last reply to you...I said that I was told by the mechanic that a hose from the transmission was leaking, but what I meant to say was that a hose from the power steering was leaking.
Thanks

Lucas? Why?
You get the best results from Mopar ATF+4, anything else in your tranny is going to cause issues, including Lucas.