I'm gonna go with 9/16" diameter and 18 treads per inch, per this lookup at O'Reilly:
Dormanยฎ AutoGradeโข - Wheel Lug Nut
Part Number: 611-127
Line: DOR
1 year limited warranty
โข UPC: 19495111276
โขWheel Nut
Multiple Applications
โขBlack Oxide - Steel
- Thread Size: 9/16-18
โขFlanged Nut - Black Oxide
- Steel
- Thread Size: 9/16-18
โขWheel Nut 9/16-18 Flanged Flat Face - 7/8 In. Hex, 1-1/16 In. Length
โขSold Individually
โขHex Size: 7/8 Inch
โขThread Size: 9/16-18 Inch
โขType: Flanged
โขSeat Style: Flange
โขStyle: Flanged
โขThread Handing: Right Hand Thread
and Picture:
The 7/8" hex size is one of the four offered on my NAPA-brand cross-rim lug wrench. But not common enough for Harbor Fright to sell in their individual $4 English or Metric (23-mm) deep impact sockets. I was able to order a single one from Amazon, but $8.
The Jam Nuts for Dicor, as MOD noted above, would therefore be 9/16-18. THAT nut is 1-1/8, by the way. But if you have an extra piece in there, like your OP seems to say, we'd need more info to try to help with that.
If God's Your Co-Pilot Move Over, jd
2003 Jayco Escapade 31A on 2002 Ford E450 V10 4R100 218" WB