It seems unfair that there are so few of these tanks with this weapon can we please have a spawn rate for these tanks?
Currently have just become lvl 30
Yeah, it would be nice if there were more tanks with linear accelerator since the 2x tanks that currently have it, are both mission specific tanks. And if you take them out, they will not respawn. Limiting the player exposure to 2x instances only.
When thinking about it 
the inactive tank at FOA4 bunker may have linear accelerator as standard issue and we may see those tanks freely roaming in the next map expansion. That would be super awesome. 
It would be interesting to see them more often, either free roaming or guarding specific locations
Hope they add it soon!