Blane isn't online very much. I can give you his cell phone number though. It is 309-737-6891.  I guess I didn't recall the missing by-pass filter, but I'm sure he can fill you in on that. It seems like he told me that it had been taken off after the last overhaul due to the inconvenient location. 

Guess I just needed my memory jogged....

I looked at your pictures, and that is not a factory loader, at least not one I have ever seen. I'd still say it had a cab as cab codes for 1655s were in the 500-600 range of numbers, and forklifts started around 700. There are plenty of gaps in that 500-600 block for cabs for other models.

Still, it looks to be a fairly straight tractor.