I'm swapping both axels out, and was turning the axels to get the locking collars on when one of the 4 floating gears in the middle fell out, (top) one. Oh Sh$%, so how to put back or is there a video out there showing how?

 

After you look at it for a while, you will probably be able to figure it out.
However, if you want to buy a video, Summit Racing sells a Richmond Gear video that shows how to rebuild a rear. Cost is about $15 I think. You can order on line. I have one of those I bought several years ago and it is very helpful. Money well spent.

 

google spider gear replacement. find a good tutorial/write-up. that's the best advice i can give.