Another Bonus for the GGTS... you can run a 510,801, or (901 with the rethreader that comes with it)
Should also note that even though the newer unit is 1/2" longer, the atty does sit down inside the tank so it really doesn't increas the length of the unit as a whole including atomizer installed my pics appear that way but there is a 510 in the old one and a 901 in the newer one and the 901 as you know is a longer atty.
I just measured both ways with a 510 atty and shorty drip tip they are both 4.5" total to the top of the drip tip.