I sent hellwig an email a while ago looking for info on the kits. I have a 14 bolt SF I plan on swapping in. Apparently the kits they sell for the 2500/3500 trucks (Hellwig 7555) have a 3 5/8ths u-bolt.
i spent way more money making my own brackets then i care to admit.
2 2”x5”x.25” 316 ss bar, had 2 drill 4 33/64 holes in these, not fun, bit was garbage by the end even with lots of lube
2 noise insulator ubolt, throw out the insulator and its the perfect diameter for a SF axle 3.375”, 316 ss.
Turns out no one makes a u bolt that is 3 3/8, its all 3,3.25, or 3.5. These ridiculously over priced noise dampening u bolts were 3 3/8 without the isolator but they would just sell me the u bolt