Axle nut

[Kodiak45]

I'll give the acetone and atf fluid a try. It sounds like the next best thing I've discovered since fluid film as a lubricant. I used to think wd40 was the all purpose tool

 

[farmer2009]

Here's a socket. 3/4" drive. But be sure you have the right size. OTC Locknut Socket,3'/'4 in. Dr,2-3'/'4 in. Hex - Sockets - 4CLL1'|'1923 - Grainger Industrial Supply

 

[Kodiak45]

2.75 is a rough estimate. But at least the socket is a realistic option, not for impact though.

 

[Soundguy]

Swage the nut.

Heat and pipe wrench should get it. Dull red, etc.