Rebuilt transmission and new torque converter from Circle D. I am now getting a metal scraping noise/grinding at 1,200 rpms in 4th gear. It’s loud and annoying. I have checked the heat shields multiple times and the IWE system (all new and holds vacuum at hubs and lines). If I give it a bit of gas and go above 1,500 it goes away. If I down **** it goes away. Here is the real weird thing. If I shift Into 4H it instantly goes away and I can’t replicate it once in 4H. To me it seems like the transfer case but I’m so sick of replacing parts on this. 2010 W/Whipple stage 2 w JDM Tune. Replaced basically every moving part in the drivetrain besides the transfer case. High performance drive shaft, rear end pinion bearing, axle bearings, cv shafts, all new. Truck has 79K. Any suggestions appreciated! Dealer thinks transfer case.