BLUEMEANIE,
That's where I got some of my info as well.
My understanding is that the bottom end is based on the GMC and the head is based on the better breathing 235 Chevy design stretched to fit the GMC block.
Of course it's all metric so none of the parts interchange with GMC or Chevy. The block is also a high nickle content that adds to longevity and I like longevity. I've also heard that the head is 12 port but don't know that for a fact.
According to Wicki the 2F has full flow oil filtration were the F does not. The last version, 3F, had fuel injection.
Cliff
