I don't know if this is of any help as the wood on my windscreen has definately seen better days. But, as far as I can see there are only small holes, not the bigger ones as on Jacek's frame. Hopefully Bob can share some pics of his frame.
Regarding the seat adjuster; David D.; I presume it's just a coincidence that the adjuster is missing on both Jaceks and my passenger seats. As David Pope mentions all seats should have the adjuster and as far as I can tell from the manual the idea was one adjuster per seat.....the funny thing however is that January '41 manual mentions two adjusters for the cab, but only one adjuster spring

. The november '43 C8 manual does mention two springs though!
I was also looking at the wooden seat spacers from my C8 today. I know there was some discussion about the originality of wooden spacers under the seat before, but my spacers even have a GM part number stamped on them!
Alex