I have a 2004.5 3500 48RE with 77,000 miles that I just did a Transgo shift kit with several of the Sonnax Valve upgrades that are discussed on TDR. 3 to 4th is very crisp but 1-2 and 2-3 are almost mushy. My issue is with reverse where there is a stutter and I have heard a metal type grind initially and it takes 3 to 4 seconds before there seems to be full power to reverse. Both bands were adjusted per FSM. I have not driven the truck with a load yet but unloaded it is fine.

Interestingly, I ended up with an extra check ball (1/4" Steel) after everything went back together. I have looked through the FSM and ATSG transmission manual and double checked the 7 check valves that the FSM called for. I did not drill any of the valve body or plates instead using the Sonnax valves. I tried to use the OEM spring etc. when the forums said to for not creating a hard shift.

The only issue that I had before the upgrade was during initial launch, forward or reverse, in that it took a very heavy foot on the pedal to get a heavy load (14,000 pound) started.

The parts that I used were,
Transgo shift kit
GM Pressure Control Upgrade
53397A Governor Pressure Sensor
Sonnax 22771A-02K Pressure Regulator valve
Sonnax 22771-09 Manual valve
Sonnax 22771A-01 4 spool valve
Billet Strut and Anchor
Billet Accumulator piston
Removed the drainback valve in coolant line
Gauges in pan and hot line - staying less than 150d unloaded
Amsoil to top off system, about 2 gallons.

First time posting but have enjoyed TDR since 2006. Any thoughts would be appreciated.

David