Why are there two different size brake fluid reservoirs for the 33 Hot Rod. Both are firewall mounted & polished one has a tank depth of 2 inches and the other has a tank depth of three inches. The smaller one has a knurled screw on cap and the other has more of a toothed design to the screw on cap. I have the Wildwood disc brakes on the front that were included with the kit and stock Ford disc brakes on the 1996 Ford Cobra 8.8 rear end on the rear. Which of the brake fluid reservoirs is recommended?

Thanks
Vinny