The drawing only give the detail for the left side tank and there is no detail for the right side tank.
They are not the same as the right side tank needs to accommodate the reversing pole reach rod. To fit this tank (or remove it) the fixing bolts cannot be soldered into the tank as they will not clear the frame plate work assuming the reach rod clearance for the tank is restricted by the splasher plate work.
I have just put blind bushes in to overcome this and the tank will slide in and out. No doubt there are other solutions.
Indeed,the drawings show no detail differences concerning the right hand tank. Maybe the photographs recently posted here on the 4150 group's website might be of interest. The third photo down seems to show a tunnel for the reach rod and drivers,which widens towards the front-presumably because of the vacuum pump drive or its connections?
Built a Tubal Cain 'Trevithick' engine (as the 'Catch Me Who Can' loco).
Building GWR 5101 class tank loco,and a 5" gauge BR Standard Class 2 tender loco.
Planning a 'Large' Metro.
The reach rod does not need the complicated tunnel of the full size. The base of the tank can be simply "stepped" to form the space needed for the reach rod. The model does not need that extra water space that the full size needs.
The rods which operate the sand boxes also share the space used by the reach rod within the right hand tank area, poking its head through a hole in the saddle plate.
Those rather innocuous looking connections between the base of the side tanks and the bunker tank (passing behind the cab steps) are massive rectangular passaged castings which even two men would struggle to lift! 5" Gauge does have its advantages.