Transmission swap

If it is a P71 transmission as well it will work. The base version of the transmission will bolt up and operate but can have error codes as the control system is programmed a bit different, and the police version is built better for better shifting and longer life.
The base transmission can be upgraded to work but it's usually better to start with the P71 version as it does have a few unique parts.
What is the issue you currently have?

So, is there any other transmissions that will work?

The police versions are built better than the regular cars or trucks and as such you really want to either replace it with a P71 version or rebuild the one you have. You need ID code version 7W7P-CA if you want a bolt in replacement.

Where do I find the code?

It is on the transmission stamped on the housing, The faster way is to simply look at the vehicle, the 7W7P-CA is only used in the P71 option, So Police cruisers and some Taxis are the ones to look for. If you are looking for a used one, try car-part.com and see if any yards nearby have anything. Or if you have a P71 now the transmission can be rebuilt. The other option would be to have the PCM reprogrammed to remove the options coding, then you could use the common transmission but after having the programming done and getting the other transmission you would have spent as much as rebuilding the existing transmission.
What is the current problem? Slipping, burnt fluids?

Slips real bad in first and third, but will hold the gear with no issue wot or 10 %.

Sounds like time for a rebuild.