I've got an 85-86 T-5 in my 37 Chevrolet 1/2 ton pickup truck. I also have a 1985 S-10 Chevrolet Blazer Owner's Manual that specifically indicates that Dexron II, which has now morphed into Dexron III, is to be used in that particular T-5 NWC transmission.

"Truckin' Around .......... Since 1937!"
My name is Joe and I am addicted to Classic Country Music. I just can't hep myself.
Operators are standing by to take your calls!
Now cruising in the Passing Lane