Is this car safely jacked up? I've got in on 4 jack stands. The rear axle has to hang free as I'm going to remove the transmission.

I'm going to be under their for a while. Any way to make it safer?

It's about 18' in the air. Is that enough to slide the transmission out?

 

Here are some more pictures

 

Generally, I would say yes. But in some of the pics it looks like you have it supported by the soft part of the floor.
If you want to be sure, take 4 pics and post them. Use a trouble light for lighting, and get that camera as close to the ground as possible so you can take an upward angle of the contact point so we can give you a better answer as to whether it's safe.

And yes, 18" is high enough to get the tranny out.

 

Ok Thanks. I'll take some better pictures with a real camera and not a cell phone.

 

Man that setup would hold that car forever lol, I'm still using cinder blocks and 2X6 pieces on gravel and dirt, there's a fine line between bravery and stupidity and just plain *****. cheers