Most likely a regular 440 found in light trucks and cars of the same vintage.

That said, I have seen winnebagos with steel crank 440's (yes I know the difference) as late as 1980 (yes I know the 440 stopped in passenger cars in 78) in a class A chassis.

Heads are taller than regular passenger heads, and use a smaller plug, due to the added cooling passages.

I am aware of the 413 industrial motors used in earlier winnebago's, and those were not the same at all.

The only notable visual difference with these, is that there is a large gap (about 1/2 inch) between the valve cover mounting surface, and the intake. On a regular passenger motor, the valve cover is nearly touching the intake. That said, the intakes do interchange. The plugs are still straigh, not like the 413 which had angled plugs like a small block