Hastings... ... ..... yep, yer starter is bolted by 10-1. 5mm bolts with 10mm 12-point head. They are torqued to an astounding 45ft/lbs. (I looked it up) How do I know? I used a clicker torque-wrench set at 45ft/lbs. My shorter handled ratchet wrench didn't give me enuff leverage.
When I replaced my starter contacts with Larry B's, since all my sockets are 6-points, I went out and bought a new short 12-point 10mm socket and immediately rounded the corners of the top mounted 12-point bolt. There is a slight "bulge" at the socket snap-joint that prevents a straight shot at the starter bolt head. I went out and bought a NEW DEEP 12-point socket that by-passes the slight miss-aligning interference bulge.
But HERES THE TRICK, super-glue yer 10mm 12-point socket onto yer starter bolt and you won't have alignment snap-off problems.
Once you break yer 45ft/lb torque, you can finger unscrew the bolt the rest of the way. Use acetone (fingernail polish remover) to un-glue yer socket from the bolt. Simple, eh?
BTW, Cummins p/n: 3903834 for replacement starter 12-point bolt... ... ..... Dell (WA)