As pictured, standing up, horizontally, it is a T section made from 63 mm OD tubing.
Vertically, there is a 38 mm tube straight through, making for a 5-way manifold.
Two of the three flanges on the T are of the same size as on both 38 mm tubes, 69.5 mm, with a 34.5 mm dia hole.
The large flange has a 114 mm dia with a 61.6 mm hole.
The smaller flanges have 6 bolts on a 29.4 mm radius. They are probably UNC