There metric bolts dont know the with from bolt to bolt. Are you makeing adapter plate to bolt them to your rockwells. I just starting to make mine. But im drilling out the the yota flangers so i can run standered bolts in mine. My adapter is like a inch thick. And going to use allen bolts. There grade 9. Grade 8's rush to fast and they tined to bented some. I'm trying to make mine bolt to the adapter. not just stick thow the adapter and have a bolt on the other side.One thing to if you have some one make them they need to be very cherw. No run out at all. I mean like with in .002. Your shafts will be spinning very fast. 