Rear differential drain plug

[o1gnah]

Trying to figure out the size of the rear differential drain plug on my 73’ 318 Auto charger. I believe it’s a Dana not exactly sure the size 8 1/4 maybe? I’ve tried a 3/4 square socket (to large) also tried 11/16 12 point socket almost grips but slips under tension a open ended 17 is not to large and a open ended 16 is to small. I attached some photos using a caliper it read ~.667”.

 

[eldubb440]

 

[Belvedere408]

Looks like an 8.25. I usually just use a crescent wrench.

 

[Mackman]

8-point socket

 

[o1gnah]

I dislike the crescent, feel like they always slip and strip as why I haven’t tried.

 

[33 IMP]

.667 is .020 under 11/16. I'd try an open end 11/16, but I wouldn't use a lot of force. It looks like somebody already rounded the corners off. Absolutely positively has to come out? Eight point socket.
I'd try a 11/16, but a 17mm might be better.
I'd also try an open end 17mm before I bought something new (17mm≈ .669).
Edit:I'd remeasure with your caliper, picture looks like you have it cocked a bit.

 

[R413]

Get a quality crescent wrench that the moving jaw stays square to the top and they won't round off things.

They sell 8 point sockets for these square plugs.

They are pipethread and don't need to be very tight, they won't come loose if you put 25 ft lbs on them, not as tight as you can.

 

[Rishi]

You may want to heat up the case, around the plug, with a torch. After, chill down the plug as best you can. Those rounded corners are looking like the plug is near end-of-life.

 

[j-c-c-62]

You lost me on "drain plug", it's the fill plug, I would replace it
when you get it removed, being it is in the final stages of being rounded it looks to me.

 

[j-c-c-62]

I dislike the crescent, feel like they always slip and strip as why I haven’t tried.

Maybe use a metric crescent?

 

[YY1]

Maybe use a metric crescent?

I have one.

 

[YY1]

Agree it looks like it's at the end of it's useful life.

Maybe a big one of these-

 

[Don Frelier]

A small pair of vice grips and a 2lb mash hammer.
It should come out pretty easily.

 

[33 IMP]

Agree it looks like it's at the end of it's useful life.

Maybe a big one of these-

View attachment 1928762

Ive got a similar set that I got from HF. I don't even remember why I bought it, but it did what I needed.

 

[YY1]

Mine are Kobalt, from Lowes and don't go that big.

Had to use them after nothing else worked on my Renegade's oddball oil drain plug.
M14 with a 13mm head!
WTF??
The "standard" for an M14 bolt is 18 to 22mm head.
I found a replacement that is 16mm at least.

 

[69ChargerR/TSE]

This is what I used on my 8 3/4.
5/8, 8-point socket.

 

[Mick56]

This would probably work pretty well. 1/2" drive on one end, 5/8" square on the other.

 

[R/T Boy 67]

If all else fails, a small pipe wrench should work. Nothing grips like a pipe wrench.

 

[YY1]

I tried that on my drain plug with a 24" cheater bar- no bueno.

Those "easy-offs" cut into the workpiece and really work.

I did need to use a 1/2" drive impact, though.

Not possible with the pipe wrench.

 

[Project66]

Knipex Cobra? I have the Irwin knockoff version and something about the design makes it really bite on weird or rounded-off bolts. It's my go to when all else fails.