Gears not catching

I have a '72 GMC 350 V8 truck. I recently removed the tranny pan to replace gasket, filter and drained old fluids, then I resecured it. I then added 3 qts of fluid, cranked her up and waited 10-15min to check levels. Dipstick is dry. I waited another 10 min and same result, bone dry. So I turned truck off, looked under hood, under truck/on ground and no leaks. I recranked and waited 10 more mins, still not reading any levels, bone dry dipstick. I put truck in reverse, accelerated and so I placed it in drive and still got nothing. At this time, I am not sure the fluid is reaching tranny. Everything worked fine previously. I then added 2 more qts of tranny fluid and still got no dipstick reading. Now, I am heated and feel like a dipstick because I dont know wth is going on. Could it be when I drained tranny that is is really really dry and thirsty? Is the fluid relubricating other components of tranny before it reaches pan area? Can someone please help me and let me know what is going on. Thank you!

'72 Sad Dipstick of the bay