PB Blaster "Caution"
 

Good news.
But consider leaving one side intact so you have smething to twist a bit
when the pin begins to move and keep soaking in penatrating fluid to
help lub it on the way out. If you take a fitting or small diamiter pipe
just larger than the pin that someone can hold on the other side of
where you are hammering the pin the impact will be much greater and put
less strain on the aluminum cast. Aluminum fractures easily.
Let us know how you make out.
Good Luck.