the 4.10's really do go well with the 3.9's though. If I didn't do any highway at all or was switching my truck out to dedicated race, I wouldn't think twice about 4.56's. A 4.30 would be the sweet spot, but they don't exist for the chrysler 8.25 or even the 9.25 that I know of. The V6's just don't have the down low torque that the V8's do, and the 4.10's make up for it.
Think of it this way. V6 (3.9L) = 75% of a V8 (5.2L). 3.55 is 78% of 4.56. So kinda/sorta by the numbers, a 4.56'd V6 (3.9L) should produce about the same torque as a 3.55'd V8 (5.2L).
That said, the 42RE behind the V6 and the 44RE behind the 5.2 both have a 2.74:1 first gear (keeping the comparison above valid), but the 46Re behind the 5.9 uses a 2.45:1 first gear.
Without all the words:
3.9 L = 75% of 5.2L
3.55 = 75% of 4.56
3.9 L = 66% of 5.9L
2.74 = 111% of 2.45
net change = 74%
74% is close enough to 75% to say that all 3 platforms are close enough that both the V8's with 3.55's are approximately equal to a V6 with 4.56's.
But the loss of fuel mileage on highway would be more than significant.
Last edited by magnethead; 12-12-2013 at 11:56 PM.