99 cavalier 2200 3t40::
Id like to swap the stock 3t40 differential to a 3.33 diff? What car would i get the diff from and will it drop right in, what all would i need to do?

I would keep making a different post every day asking the same question. Maybe then someone would give me an answer. Anything is possible.

The only way I'm aware of finding out what diff a given trans has is to decode the tag on the transmission case. You might also try looking up the car by vin, but I'm not positive on that. On the 3t40 this tag is on the side cover. There are websites out there that list the transmission codes, it up to you to decipher them. Alternatively, you could just call up someone who specializes in gm transmissions, and purchase a 3.33 diff. If you wanted to go with a limited slip as well, I know Jeff at engineered performance will build you a limited slip on your choice of diff ratio, but it will cost you. Whatever you do, I recommend leaving the installation up to a professional, as the diff is literally the last part that comes out during disassembly.

If you're will to wait a while (like a year or so), I might have a professionally built, high-perf 3t40 for sale cheap, that already has a 3.33 limited slip in it. I'm thinking of doing a 5 speed swap on my car. The 3t40 will need a new converter though at least, because it is currently wailing like a banshee. But I might sell you the trans cheap if you're still interested at that point.