The data sheet says the 6C6 design is very close to the 6J7G with the exception of the inter electrode capacitances. The 6C6 is a general purpose amplifier valve but the close similarities with the 6J7 indicate a good linear characteristic and good suitability for early stage audio amplification.
The maker's name is pressed into the base cap and the indentation filled with paint.
The main image has been enhanced to show the etched lettering. Here is the straight shot.
The top has both a screening cap and an outer screening cylinder. The control grid connecting wire is welded to both grid supports.
In this image can be seen the suppressor and screen grid wires. The left most and thickest rod is a support for the top screens.
The classic envelope is 38 mm in diameter, and excluding the UX6 base pins is 103 mm tall.
References: Data-sheet, 1040 & 1043. Type 6C6 was first introduced in 1936.