Books,

Just what the subject line says.

I've developed a hum when under way whether the van is in gear or not. I've recently changed a front inner and outer bearing and degraded ball joint but alas, the noise continues. It's also a bit intermittent. Comes and goes with leaning to one side or the other, but no specific rhyme or reason. 

Bearings? Transmission? This noise was there prior to swapping my engine recently and I thought would fix with parts known to be bad ...

What thinks the experts on where I should put my hands next?

Thanks in advance!!!
Dave
85 gl, Baby Bus