Correct tool to remove Uniglide freehub? I have a coworker's rear wheel to repair.  The freehub pawls ceased engaging, resulting in free-spin in both directions.  A replacement freehub body is ludicrously expensive, so I want to remove the existing one and try a clean/service.
What is the right tool to remove this freehub body from the hub?


There are two slots, with a depth of 4mm and the shell has an internal diameter of 29 mm

A Park FR-2 has two tangs but they're about 7mm thick and will not engage.
A Park FR-3 has four tangs so will not fit.

I tried making a form-driver from some stout pipe by grinding it to size (essentially a really big screwdriver) and using the leverage of the entire rim, has broken the corners off my makeshift tool.
  
I am tempted to try hardening the ends of this pipe, but this is getting well off into the desperate category.


Here's my current collection of freehub and cassette fittings.  I was tempted to grind down the lugs on my FR-2 (front left) but that is hardened steel and may destroy its usefulness for regular usage.
What is the right tool for this job?
The freehub attaches to the shell with a big hollow bolt you access by poking a 10mm allen into the drive side. You can transplant an HG freehub body onto it, ideally one of the same or similar length (6, 7, and 8-speed UG existed) and also a matching cone and other axle hardware for the drive side so that the sealing works right. The upside here is a replacement cassette will be much more obtainable when the time comes. Wheel dish should be checked and corrected when you do this.
But, your question: to do a simple de-gumming type clean, the expedient thing is to take the freehub body off the hub, gently pry up the rubber seal on the back and take note of its direction, then run through whatever thoroughness level you deem necessary in of solvent/air/oil. Usually just working in something like Tri-flow or other light oil with penetrating qualities is good enough.
The 4mm splines take the Shimano TL-FH40 freehub body disassembly tool. This is one of the most fantastically seldom-used tools in all of bike wrenching. Full disassembly of the freehub is almost never necessary to get them working, and is very time-consuming because of the large number of teeny bearings inside. But, it is the only way to adjust acquired play out of a Shimano freehub body, which is done by removing one or more of the micro shim washers inside, which are there for that purpose.
The race that the FH40 engages with is reverse threaded to resist bearing precession loosening it. It's got things spinning against it on both sides so how that works is way above my head.
Edit: If this is 7400-level Dura-Ace, the freehub body attaches with a TL-FH10 and is only interchangeable with other similar Dura-Ace Uniglide freehub bodies. The 7400 hubs are the only Uniglide models with this caveat, to my awareness. Some hack replacements with more common units have been done, but I don't have anything to report about that.