Engine mount bracket bolts for 340.

Good morning. I’m trying to find a source replacement bolts for my motor mount Brackets. The bolts are 7/16-20 with a 1/4“ shank, and are 1.5” nominally. They are grade 5 and the ones I have have a “D” on the head. I’m having no luck duplicating this bolt through Dorman. Otherwise I’ll cut these longer ones down.

Would anyone know of a source for these?

thanks.