I hope it pans out for you...
If not i found the red block that has ventilation yesterday.Safely stashed inside the back of a burb.It's ventilated but just the oilpan from the outside.
I will wait till i hear from your latest find.I was looking for a date code on it,any idea where it would be,Casting is a 660
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