Here's some info I found on them.
https://www.dodgegarage.com/news/ar...emi-engine-quick-reference-guide-part-iv.html
As we mentioned earlier in this feature, the 6.4L HEMI V8 engine was also used in Ram 2500/3500/4500/5500 in Medium Duty (MD) and Heavy Duty (HD) truck applications going back to around 2015. While the block cylinder heads and rotating assembly offer a great foundation for building a GEN III performance project engine, the truck engine is designed more for low-end torque and heavy load applications. There are some major differences between the HD truck 6.4L HEMI V8 and passenger car/SUV 6.4L/392 HEMI V8 engines you need to be aware of. If one of these pops up at a cheap price, just know what you’re buying. The first difference is that the intake manifold has a top-feed mounted throttle body, and this design has a runner length that’s designed to make max power from 3600 rpm to 5000 rpm. The compression ratio is also lowered to 10.0:1 because of a piston change from the passenger car/SUV 6.4L/392 HEMI V8 engines.
The truck engine still uses a Hypereutectic piston w/oil squirters to reduce heat and a floating pin design that’s attached to a powdered metal I-beam connecting rod. The twin-plug aluminum cylinder head on the truck engines still retain the massive 2.14-inch intake valve and 1.65-inch exhaust valve found on the SRT and Scat Pack vehicles. The cylinder heads are also cast from high-grade T356 aluminum material to withstand any detonation and high-temps under severe towing conditions.
They have a unique casting number of 05045468AE and 68166435AA, AB, AC and AD. This head casting was also used on the 2015 Mopar Challenger Drag Pak engines. The exhaust manifolds on the 6.4L HEMI truck engines are a cast iron design that are more restrictive than the tubular style found on the passenger car/SUV applications. Most folks will probably discard the factory cast iron exhaust manifolds in favor for aftermarket headers during their engine swap project. The camshaft on the HD truck engines is also designed for low-speed torque and not higher rpm horsepower. The net result is a horsepower rating between 366 to 410 @ 5,600 rpm and torque coming at 429 lb.-ft. @ 4,000 rpm. When it comes to out-of-the-box modern performance engines, the stock HD truck 6.4L HEMI engine is not a strip blazer, but with its BGE casting block, 356 aluminum heads, and steel crankshaft, you’ll have a great foundation to build a high-performance engine combo with strong bones to withstand close to 1,000 horsepower.
