I’m getting ready to purchase a new third member for my 1969 Super Bee automatic with a 383. I’m ordering through Dr. Diff and I’m at the differential section. I’m not sure which of these I’m supposed to pick. I want a sure grip. I’m thinking the choice would be the 6 helical sure trac 2? Advice please. I have been emailing him as it sounds like he is super busy and not able to take phone calls currently.