I'm attempting to remove the pitman arm from my '53 Buick Super. Regular gear pullers won't get it. Is there a modern day puller that works? Thanks,

A special pitman arm puller is made for modern day cars,it is a heavey duty screw type puller, try pulling the arm off, you may get lucky, but if not you may have to us some heat, I usually do on cars older than about ten years, just be careful not to get the shaft on the gear to hot you may damage the seal.
Don
BCA#40498
Mich mech. cert # M119501

This may be worth a try - I used a 2 jaw gear puller to get eh arm off - it was stuck on there pretty good. Cranked it down until the puller was really "sprung" but the arm wouldn't budge. I warmed up the arm with a propane torch - and I emphasize warm, not hot, to avoid changing the temper - then hit the shaft with some pieces of ice. Some sharp taps with a hammer and it popped off. If that didn't work, I was going to go out and get the "right" puller.

Hope this helps - good luck