The 1941 MCP 11D truck I had was fitted with the water pump single grooved pullies but I am not sure if the engine was original to the truck, it was a 85 bhp motor. I fitted new seals but they leaked, Yep the plain bushes were worn. I'm sure it had only a single belt driving the gene and water pumps ?
The film company (in ALBERT PARK) I sold the truck to had the pumps rebuilt by the mob in Sth.Melbourne, plus the radiator recored for a cool $800 , this was in 1991 prices. The truck featured in a B grade movie and was seen on late night TV a few times . Here she is
https://www.youtube.com/watch?v=jf0pGxXBTyI