Did South American economies benefit from being left unscathed during WW2?

I will mainly answer from the perspective of the largest country of South America: Brazil.

This is a very complicated question, because it is hard to separate how much of industrial growth is due to not being invaded and how much can be attributed to other factors. Let's take a look at some data to see how Brazilian economy behaved during the 1928-1946 period. It is important to know that the 1929 crash hit Brazil heavily. Brazilian economy was mainly agrarian, fueled by coffee exports to pay its external debt. Over 70% of Brazilian agrarian exports were coffee in 1929, which means US$ 445M . This value would fall to US$ 180M by 1930. The value of coffee fell nearly 90%, forcing Brazilian government to buy the product, burn it to limit offer and bring back the prices. The huge economic crash fueled a coup d'état and the new government, named after its leader Vargas, decided to diversify Brazilian economy and invest heavily in industrialization. He remained in power for the whole 1930-1945 period.

Brazilian metallurgy and industry evolution in the 1930's

Imports, exports and imports composition in the 1930's

So what happens in 1940? There was an increase in industrialization and the opening of many national industries (Vale do Rio Doce, CSN), from 1940 to 1950 population working in industry rose from 14% to 18%, population working in agriculture fell from 66% to 60%, but GDP only grew 3.4% from 1940 to 1945, and this growth is dwarfed by the 7.7% from 1946 to 1950. Could we say that during the war exports were hard and that would justify the absence of growth? This Evolution of Brazilian imports and exports should give a clearer look. During the war exports went down, and after it they rose to levels never before reached. It is plausible that post-war reconstruction boosted Brazilian economy, but it is impossible to separate this effect from the previous industrialization era from the 1930's. We see also a huge change in the character of exports, since Brazilian agricultural production was pretty much stable during the whole 1930-1970 period, which reinforces the role of industry in the GDP growth at this time, rather than simply agricultural exports taking advantage of European destruction.

To summarize: I really can't tell for sure if WW2 helped Brazil economically because other factors, mainly an industrialization boom during the 1930's, cloud any impact this could have had.