['68OrangeSunshine]

I have two trucks with SM465s and Centerforce II cluches.
I've experienced the Z-Bar arms fracturing on both of them. No problems with the lower clutch rods, but both are OEMs.
Case 1] '71 GMC Jimmy 4x4 V8 350/SM465/NP205/12 Bolt 3.73 Posi. Because of throw-out bearing not disengaging Centerforce II clutch, after intital install of crate 350 [ca.1999], we had a shop weld a spliced-on '73 style threaded rod end to the original '71 lower clutch push rod. Weld is bolstered by a 3" section of 9mm gun barrel. This puts a lot of tension on the clutch fork, and any work requires a ratchet strap on the clutch fork to pull it back to ease tension. Also when Z-Bar arms were joggled to clear headers, the machinist used heat. It lasted 13 years before the Z-Bar failed. Z-Bar was rewelded and a Borg & Beck clutch replaced tho old one. Still have the Jimmy's old Centerforce II pressure plate -- resurfaced, it will go on a future project.
Case 2] '68 C/10 Stepside, L6 292/SM465/12 Bolt 3.37 Posi. Arm of Z-Bar separated [in traffic], original part @ 46 Y.O. Z-Bar had been heated to joggle to avoid Clifford headers. Got towed home. Rewelded Z-Bar. Also this truck has a Heim Joint style upper clutch rod, but one that was custom-made by my machinist [before LMC offered theirs]. No issues in 10 years. Still running the Centerforce II.