Those LS motors are the same size, physically. You'll spend too much money for a motor built for higher rpm power output than you'll reasonably use in your 40 unless you plan on spending a lot of time in the sand or mud pit with the throttle pinned to the floor. Like what was mention earlier an "GEN IV" (aluminum) 5.3 can be built with a torque and horsepower curve much better suited for daily driving and offroad use for much less. I'm building one for mine. Saying "its got a 6.2" is simply bragging(or compensating) for MOST of our trucks here, unless, like I said earlier it was built for a specific purpose. Even then, a LQ4 6.0 out of one of a million 2500HD chevy trucks ruining around will out perform that 6.2 after spending some money on hop-up parts and you''ll still be money ahead of the 6.2... my opinion of course. The iron block 5.3, and 4.8 for that matter, as well as their aluminum brothers are all AWESOME motors. Get one, change the cam, be happy!Is there a reason most people are going with 5.3 V8 swap over the LS 6.2? is there a size issue?