I have a 2019 Crew Cab LT 4X4 with the composite overload leaf springs. What I have found out from the aftermarket is there are no restrictions on lift blocks with the composite springs. They won't specifically say yes the lift blocks work with the composite springs but I have spoken with 2 different aftermarket manufacturer's support lines and they are saying "we are not getting any complaints or having any issues with the composite leaf springs". On the other hand when I called the GM support line directly they said that they didn't know anything about it and they probably couldn't tell the consumer if they had information. I have talked to multiple GM dealerships and they didn't even know the lift existed. This kit is not excluded by VIN when mine was ordered they used the VIN to find the parts available and when it arrived at the dealership and I had dropped my truck off for installation they called me and told me it was incompatible because of the composite springs and 5.3 motor... They contacted GM corporate to find out why this would matter and according to the GM parts general manager they have not tested the lift with the composite spring trucks. He indicated that they were currently undergoing testing and should be available for install in the next few months. I agree with others on this thread that GM doesn't want consumers building cheaper trail boss trucks. I ran the numbers and when I bought my truck and TB lift kit I saved $8k over buying the trail boss. I think GM is messing with the consumer on this and I don't believe that they will allow it to be installed anytime soon. That's just my 2 cents.
