Diesel coolant question on the 6.2

[72timemachine]

Getting a bit dizzy reading about antifreeze and sca additives for my 1984 c3500 dually with the 6.2 diesel engine. Do not recall all this fancy antifreeze back in 1984.

My factory manual says use GM 1825 m but goes on to say the new coolant (1052753) conforms to the GM 1825. I am not a cheap skate, but this being an older system is it possible to use Wal Mart SuperTech brand with an sca additive, distilled water (I would buy the full strength and mix it) and check it with some test strips? Now the label on the SuperTech jug only states that it is for use with any make or model car or light truck...sort of a bold statement yet says nothing to the effect of meeting ASTM D-4985 specification aka low silicates.

I am NOT using an aluminum radiator but that crazy huge factory copper 4 core beast.

One more question I cannot seem to get an answer to in the manual is:

Is this engine considered a wet sleeve design? Just would like to know for my own good thanks.

Thank you for any help.