I just googled electric Chevy van and there’s a 1989 electric van white whine that had some info on it.
Under batteries this is what it said.
BATTERIES - 33 Saft STM-5-200, 6.00 Volt, Nickel-Cadmium, Flooded
No longer in production, Originally made for PSA (Peugeot/Citroen). ~40kwh pack capacity. The blocks are arranged in a custom-made stainless-steel carrier that hangs from the frame underneath the van. This makes for good handling with it's low center of gravity and stiff springs. There are no EV components inside the van, so the full space is usable. The battery tray also has 2 fans and ducting to cool the batteries when used in very hot climates, here in San Francisco the fans are not needed though