Yes, all have the plug beside it. I have a 717 and two 925's (3769). If there is a block out there that does not have that smaller port, I guess it IS possible that it is full flow only, but not real possible for them to be backwards since that would require a major internal change.
Since I have the 261 document on my site, I get phone calls all the time about this issue. Each time everyone has the same dowel action. The dowel hole is 1-5/8 inches deep. When out, bypass, when all the way back, full flow. The way to test is described above. With bypass, about 12-18% of the oil is filtered, with full flow all of it.
As you said though, there could be a block out there that is completely different but with the 717 casting code?
