Bolt size on track bar connection to axle 08, 2500

[Ed Elzy]

Looking to find bolt size to preplan a job. Looking for the size of the bolt that connects the track bar to the front axle. Nut fell off the back, it has oblonged the front of the hole on axle housing. Will weld in steel plate to fix hole. Need to find bolt size to weld nut to steel rod so I can securely tighten bolt.

Any help is appreciated!