Should you change just the rockers or the tappets as well, rockers would probably be the most abused part??

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2014 Chevy Silverado Crew Cab 5.3 Ecotec LTZ Z71 4x4
2012 Ford F-150 XLT EcoBoost 4x4
2007 Chevy Silverado 2500 HD D-Max 4x4
1996 Dodge Ram 1500 4x4 (just about dead)
2006 Jeep Liberty CRD

Sometimes the rollers wear out and sometimes the lash adjusters break.
If you are unsure, tear it apart, assess, and buy what you need.
But I recommend replacing all of them. Rockers and lash adjusters.

When I replaced my head at 160,000 miles, I found that all my old rockers and lash adjusters were still in good shape. But I had already purchased new ones so I installed them anyway.

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U.S. Army Retired

Change both. I guess you could feasibly change just one or the other, but as involved as this process is, why take any chances?

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Silver 2006 KJ 2.8L CRD Limited:
GDE ECO Tune / Fumoto Valve / E-Tecno GX3123 7v Glow Plugs / 2nd Gen Fuel Head / Mishimoto RED Hoses / Rockers/Lifters @ 114k / Hayden FC + 11 Blade Nylon / Sears P1 Battery / Transgo 45RFE-HD2 Reprogramming Kit / Timken Front Bearings