Is the 4BT pretty loud in the cab of your 55? What size tires are you running to get the mileage you are getting?
I put lots of effort into sound deadening and the 4BT is not as loud in my pig now as the SBC was in in the same rig before. I still have 4:10 gears but I have 35” tires, an 8% over drive transfer case gears and a NV4500 with .73 overdrive so I’m around 1850 RPM @ 70 mph in high gear.
More info with pictures of my 55 here: Target carrier
