[William]

X trim tag codes entered production at the Norwood plant late Dec '68. They were not used at the Van Nuys, CA plant. X11 is never a Z/28.

Z/28s used the standard 11/16" front sway bar. There was no optional rear bar for '69. There was a retrofit rear bar for '67; they are extremely rare and were never installed in production.

For '69 Chevrolet used the new interlock motor mount on Camaros with the 302 and 350 engines. This mount requires a different frame bracket that is 2-1/4" wide. The non-interlock mount bracket is 2-1/2" wide and about 3/8" taller.

Power front discs, 12 bolt axle and 4-speed trans were optional or included with other engines, not unique to the Z/28.