My history with junkyard transmissions has been... very bad.
In my car, the original automatic transmission was slipping like crazy, jerked around, wouldn't go into drive, etc. I was able to find a used transmission from another '94. I drove to pick it up, took it to my mechanic, and had him install it. After $500+ for R&R, three months later the trans gave out again. drove it until it wouldn't go into drive at all.
After previously going through the same with my 2000, I gave up and let it sit for a while while I saved up for the 5speed swap.
If I had the need again, I would rebuild my own before going back to a junkyard. But, that's just from my own experience. You might be able to find a wrecked car that was otherwise in great condition, but with transmissions there's no way to look at it and see how the internals are. It's a gamble unless you can actually drive the vehicle before it is pulled... which is a very unlikely circumstance..
Best of luck to you.