latex stuff about the equal sign

$$
X = ^d Y
$$
This is not a good way to display equal in distribution.

Here is one hack (gotta be a better way). the b here says to put the equal sign on the bottom

$$
3 \begin{array}[b]{c}\alpha\\[-2ex]= \end{array} 5
$$
%b for bottom in \begin{array}[b] to mean the equal sign goes below
% could put it in \be \ee instead of the two dollar signs