Tip's on getting the coolant out?

I have drained the front radiators and only able to extract around 5 quarts of coolant. The manual states it will take 4.8 gallons of coolant. What is the best way to get most or all of the coolant out? Drained the radiators for 24 hours. Thanks for any help guys!

 

When I drained my 360 I parked it nose down on my moderately steep driveway. I didn't measure what I got out, but it was a lot more than 5 quarts. All I did was open the radiator taps and remove the expansion tank cap.

 

Thought I would report back. Used air thru the fittings on my airlift tool to purge out another gallon or so of coolant and then vacuumed, refilled and started the car. Worked perfectly. Ended up getting out about 2.5 gallons of coolant and it replaced with the same amount. Overfilled the expansion tank a little so had to draw out a little but went thru warming cycles, heater on and cooling fan cycles several times. nice tool that airlift, recommend it to everyone.

 

I plan to open the front radiator drain while mine is on a lift at work, then just lift the rear of the car up a foot or so to bring all the coolant towards to front to drain.