Did you have to modify the thermostat outlet for your truck?
I had to, to use the upper dual housing on my crewcab with the original 6.2 the outlet had to have a different angle for the hose to clear.
You may have to do a little fabricating for your throttle linkage and high idle solenoid.
I have a dual setup on both NA and turbo'ed engine.On the NA engine i had to rework the angle for the top rad hose and do some work to get the throttle cable hooked up..And on the 97 turbo engine when i changed to mechanical pump i had to move the high idle solenoid and build a bracket for the throttle cable.The upper hose outlet was made for the 97 so the hose route never changed.
Let me know if you would like to see what i did if you run into issues.
Thomas
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews