https://www.allpar.com/trucks/ram/2014-heavy-duty.html
1 2 3 4 5 6
66RFE 3.23 1.84 1.41 1.00 0.82 0.63
68RFE 3.23 1.84 1.41 1.00 0.82 0.63
https://www.allpar.com/mopar/transmissions/ZF8.html
8 speed
The tall first gear allows for early lockup of the torque converter clutch.
Gear 1 2 3 4 5 6 7 8
Ratio 4.71 3.14 2.10 1.67 1.29 1.00 0.84 0.67
Here is all you are missing with a 6 (excluding mpg)
1 - 4.71
3 - 2.10
6/7/8 the same
It the seat of the pants dyno might like the differences and maybe the mpg.
It is difficult to tell because I can't find Ram's info for 2019 But, It looks like you pick up 1,500 of towing with the 8. BUT THAT CAN BE DUE TO OTHER FACTORS and not the transmission.
https://www.tfltruck.com/wp-content/uploads/2019/01/2019-ram-hd-towing-chart.pdf
https://www.ramtrucks.com/assets/towing_guide/pdf/2016_ram_2500_towing_charts.pdf
1 2 3 4 5 6
66RFE 3.23 1.84 1.41 1.00 0.82 0.63
68RFE 3.23 1.84 1.41 1.00 0.82 0.63
https://www.allpar.com/mopar/transmissions/ZF8.html
8 speed
The tall first gear allows for early lockup of the torque converter clutch.
Gear 1 2 3 4 5 6 7 8
Ratio 4.71 3.14 2.10 1.67 1.29 1.00 0.84 0.67
Here is all you are missing with a 6 (excluding mpg)
1 - 4.71
3 - 2.10
6/7/8 the same
It the seat of the pants dyno might like the differences and maybe the mpg.
It is difficult to tell because I can't find Ram's info for 2019 But, It looks like you pick up 1,500 of towing with the 8. BUT THAT CAN BE DUE TO OTHER FACTORS and not the transmission.
https://www.tfltruck.com/wp-content/uploads/2019/01/2019-ram-hd-towing-chart.pdf
https://www.ramtrucks.com/assets/towing_guide/pdf/2016_ram_2500_towing_charts.pdf