I used an acidic solution on my trailer fenders;however, it only came back after 4 mos. or so, what an eyesore! I took them to get powdercoated 2 weeks ago for $200 total. Should have done it long ago.

cant you take the screws out of the block of aluminum and split the two pieces apart?

I believe that block of aluminum is his puller.

Just for the record , like one of those consumer reports , I had a job last year to dismantle some high end outdoor furniture for re-finishing . The furniture was powder coated aluminum and the bolts were stainless . Of course thanks to this gawd awful salty environment the aluminum had seized the s/s bolts to their threads in the furniture and we tried that Freeze off shyte. A total waste of money . Once I realized that all I was going to do was snap the heads off of the bolts we took the stuff to a machine shop and they extracted all the bolts and broken studs like magic.

That would make more sense ;)

Seems like brute force is the single biggest tool in the box. I had tried twisting it with a 12" wrench several times with no luck. After I got it moving a little yesterday, I got a 24" wrench on the clamping block and slowly got it rotating back and for a few degrees. Went back to using the jacking bolts, and finally got it moving and out. It's interesting to note that the muriatic acid attacked the bare aluminum far more than it did the oxidation. (Now you know why aluminum oxide is used on sandpaper...)
I couldn't get the anodized tube to unwind from the stainless fitting, even though I had used an anti-corrosion compound when I put the parts together (9 years ago), so I resorted to using a slitting saw to split it in half. (Exit $300+.) Now it's all cleaned up, sanded and repainted where the acid stripped the paint on the transom shield. Once the paint has cured, I'll clean up the bore in the casting with sandpaper and scotchbrite, then assemble it all back together with copious amounts of waterproof lithium grease. (And dismantle and re-grease them at least once a season from now on...

By the way, here's the breakdown of what I've been working on. Parts 25 through 32...

WOW
That is some serious bonding between pieces

Yup. A nasty problem defeated by patience and persistence... ...and brute force.

If you look up what anodizing is, its an oxidation process that changes the surface composition. Its that oxidized layer that protects the aluminum and makes it tougher.