Some fluid will for sure leak out. The back is lower than the front.
You probably need a U-joint anyway,or at least a service; so just take the yoke off your current driveshaft; it only takes a few minutes.
If you are taking them out together,thru the engine bay,then you will need an engine tilter. The assembly has to be angled rear down, ever more as the lifting proceeds and the rear yoke will eventually want to gouge up the firewall. For this reason I install a plastic plug there, that is made for the job. But in either case, if you don't drain the oil, then it's all gonna pile up in the tail, maybe taking some sludge with it, and it will try to dislodge whatever plug you installed. Sometimes you get a gusher.
My best advice is to drain the pan beforehand, clean it, and bolt it back on. And then wrap the tail with an old towel, and secure it. Then when the assembly does not come out exactly as planned, the towel will save the firewall.
Yeah, you can do the job without the tilter, but I highly recommend that you don't try it. And I highly recommend that if you don't have a tilter, to separate the trans off the engine first. Yeah I know it's a pita, but so is repairing a firewall gouge, or multiple gouges; or replacing the windshield if chit gets away on you.
