Both involve a substitution of metric for an SAE size.
1. I replaced the short extend and retract P/S hoses tonight. My flare nut wrenches don't fit on the end that goes into the control valve so I had to use an open end wrench. I think it's supposed to be 7/16" but on both those that I took off and the new ones I put on (delcos), an 11 mm fit much more snugly and allowed me to not round off the nuts.
2. This one involves the diff fill plug. I think a 5/8" open-end is the optimal tool here, but there's not much room to turn it with everything still installed. A socket and ratchet with extension work much better, but I don't have square or 8 point sockets that big. I tried some different 12 point socket sizes to see if there was one that would grab it snugly and ended up with (I think - it's been a week or two) 19 mm. Worked perfectly to get it off without rounding and to snug it up again when I was done.
Just thought I'd share - I'm sure there're other methods that work just as well or better!
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1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.