Good to know the IRS is new. Hoping it will be just as strong as the vette one. 6L80E is also good news. No more stage whatever wasting money on unreliable transmissions. Here are some specs on the trans................................................................................................................................................. 4L60E gear ratios: 1st 3.06, 2nd 1.75, 3rd 1.00, 4th 0.70. Reverse 2.294...............................................................................................................6L80E gear ratios: 1st 4.02, 2nd 2.36, 3rd 1.53, 4th 1.15, 5th 0.85, 6th 0.67. Reverse 3.06 31% more gear in 1st. That pretty much eliminates the need for really steep gears to get out of the hole. It will make 3.42s look like 4.49s off the line. 6th gear being slightly taller will give little lower cruising HWY rpm. So it will make those 3.42s look like 3.27s. Excellent shift extensions in the middle. A high slipping TC won't be required to keep the rpm up after shifts. Maximum Shift Speeds: 4L60E: 6100 rpm 6L80E: 7000 rpm Maximum Engine Torque: 4L60E: 360 lb-ft 6L80E: 520lb-ft Transmission weight: 4L60E: 162lb (wet) 6L80E: 212lb (wet) It's only downside is 60 more lbs.