Well, it is possible but it depends on what type of hard disk they’re using in there. You may want to check the device manager settings to see what type of hard disk it is using. See, there is one main issue with 1.8” hard disks. They all don’t necessarily use the same connector as there isn’t really a standard connector like there is for 3.5” or 2.5” disks.
Toshiba puts their connector at the back much like the 3.5” and 2.5” disks with a similar pin layout. Hitachi puts their connector on the side of the hard disk meaning that they are not compatible in terms of mounting. I believe the pin layout is the same though.
So, lets say you have the Toshiba in your TR and a Hitachi in your U70…there’s no way to swap them. The cables inside the systems are custom made so you wouldn’t be able to mount one in the other. Your only bet is to find a larger capacity version from the same vendor to ensure it fits.