that shipping thing is correct, they are shipped dry for liability reasons, trans fluid is very slippery on the wooden floor boards of the straight trucks, but anyway,
it all depends on how long you plan on storing them,
dry =
1)front and rear seals will dry requiring replacement before put back into svc
2)clutch packs will NOT swell which is good for their life
3)residue trans fluid WILL stick in the valve body components which might change the trans behavior when put back into svc, but clears up in a few hot/cold cycles
wet =
1)good for front a rear seals
2)clutch packs and bands swell, decreasing thier life when put back into svc
3)valvebody stays clean
when i mean swell.. i mean in as little as a year to as much as 5 years.. depends on their current condition, it takes 4-5 years for brand new clutch packs to swell,
pump and rear seals should be replaced anyway before putting the trans back into svc, so i say leave it dry
a friend who owns a performance trans shop for bracket cars stores them dry WITHOUT their valve bodies in them, he cleans out the valve bodies and stores them dry as well.. but they are 100% clean