speedometer and low oil level

I have a 1997 Cutlass Supreme. A few days ago, the speedometer quit working and my low oil level light comes on every time I start the vehicle.
I tried replacing the output speed sensor, but that did not do anything. I could use some advice because the dealer quoted $2500 dollars for a new transmission.

Welcome to AF, how was it determined the trans was bad relative to the speedo, the low oil level may just be the sensor in the pan, the other issue sounds like a priority.

how was it determined the trans was bad relative to the speedo

Well, the car is not shifting correctly. It used to shift at 2000 rpm but now
anywhere from 3000 to over 4000 rpm. When I take off, it's like it's stuck in
second but I can punch it up to about 4000 and it'll shift. But then, when I slow down, it stays in the higher gear. I just drop the shifter into first (1) and
I think it goes into 3rd.
I assume that the speedometer not working has something to do with it not shifting.
Oil light has not came on last 2 days.(knock on wood)

Correct, the trans is in default electronically , usually the speed sensor will correct this unless they diagnosed some catastrophic internal failure, still need a detailed diagnosis how they determined the speedo failure is related to needing a new trans.

Correct, the trans is in default electronically , usually the speed sensor will correct this unless they diagnosed some catastrophic internal failure, still need a detailed diagnosis how they determined the speedo failure is related to needing a new trans

Sorry, no one has actually told me that the speedometer failure has anything to do with the transmission not shifting properly.
I let someone drive my car and they said that the problem was not even worth fixing.

Hi, It's me again. I just have a few more questions...
First, where is the input speed sensor located?
Second, What should I do?
As stated earlier, I have an Oldsmobile Cutlass Supreme with a non functioning speedo and a tranny stuck in first. Any help would be appreciated
as I am looking at spending $1300 on a new tranny.

Have you determined the sensor is bad by having the car scanned to see any speedo input to the pcm? Autozone.com repair guides has the basic info.

on my 97 cutlass im having the same problems. about 3 months ago i put in a new speed sensor and it run like new. 2 days ago my speedometer stop working and now the trans is acting up again.