I've never used a pickle fork. Your hitting it wrong. Never hit the threaded portion. As you found out, once the nut is tighten to spec, it really doesn't do anything. It's a backup safety thing. It locks the tapers together. To break a taper you need to hit the female portion of the joint/steering arm. You put the nut on to protect the threads from glancing blow & prevent the tre from dropping. It takes a pretty good smack or a bigger hammer. It'll break loose.
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You can borrow a tie rod puller from O'Reilly that works great for the Toyota TRE's. It looks like this one...
They have a little chart of all their tools they lend out. For this one it's like $36... and when you return it they refund you. It doesn't slip off and it works perfect for our style TRE's.