If the Duramax has a by-pass built-in then
7.8” hanging at a angle full of oil vs a 10.3” hanging at the same angle full of oil, this would be more downward pressure against the cast housing.
yes, however the difference is a couple of foot pounds. There are guys hanging whole turbos off the side of the block. Im not arguing necessarily that one is better then the other, just that the difference in force exerted on the block by the two filters is trivial compared to other loads on the engine that it sees daily under normal use.
if the thing was made of depleted uranium (density of 19 g/cm3) then id say your totally right, but there's just not enough mass present to argue that the cast housing is in danger of failure from the increase in load from the longer filter.
Also the values i used are very inflated, the real world numbers would be much lower if you did the math correctly with an integral equation for total torque applied.
based on 2" radius for filter (factory diameter is just under 4" per google) at specified lengths above. This is not the true torque, this is the maximum torque, as if the filled filters were hung off an empty filter from the tip.
Rough torque for factory filter: 3.3 foot pounds
Rough torque for longer filter: 4.3 foot pounds