We remember Maz as the hero of Forbes Field, wearing the sleeveless uniform of the 1960s, but he did stick around long enough to play at Three Rivers and wear the doubleknits.

Nice chaw, Maz.
This other pic is interesting. I'd guess it's from spring training, 1962, and the Pirates have just busted out their new uniforms, with the numbers on the front now. Yet, Mazeroski is still wearing the old, triple-striped socks, rather than the two-stripe socks the Buccos changed to that season.
Were the Pirates rolling out the unis in two stages? Odd that they'd wait on the socks, which have to be easier to manufacture than the uniforms, which require measuring. Or was Maz using old socks in ST? Again, odd, since you'd think it was the uniforms which were harder to clean and more important to preserve. Inquiring minds…don't really want to know, but are intrigued enough to note the discrepancy.