To me, the down side of the 518 is the crappy 2.45 first gear ratio is a carryover from the 727. The 700R4/4L60E has a 3.06 first gear but second is a tall 1.62. That is a wide spread, sort of reminds me of the 833 OD 4 speed.
It may seem like crap on an rpm formula but that 2.45 is what we consider close ratio. This is ideal for powerful engines. You put the deep ratio in the rear and now you have less rpm drop between gears.
The 3 something ratios you speak of are from an era of gutless engines. The 4L60E and 833 OD are for moving heavy vehicles with weak engines off the light and with no consideration for big rpm drop between gears.
I hear what you are saying but until you have tried both, don't be shy of a tall 1st.
On an unrelated note. This is 518 vs NV3500. They soak up alot of power. I did a 518 swap in a truck. While climbing a bridge near me. I had to turn off the overdrive and unlock the converter to climb this bridge in 4rth. When I swapped to the 5 spd manual. At the same rpm I could easily climb the bridge in 5th gear. The same truck had a 3 mph increase in trap speed and 2 mpg improvement.
I am not saying a Silversport 4L60E would be any better than a 518 but after seeing the numbers for me, I'm not a fan of 518. The rpm change seems to be the only thing talked about but poor mileage in Ram1500's make me thing they are not the way to go.
