I am working on the Speedwitch kit of the XM 25/26. One side will be from the C&S 13500-13999 series and the other side from the FW&D 7201-7700 series. The prototype photos included show C&S 13781 (1-1965) and FW&D 7415 (10-1953) with gussets at the top where the vertical and diagonal braces meet while FW&D 7234 (10-1953) does not have the gussets. Curious if anyone knows at what point these gussets began to be applied?
For those contemplating building #106, in dry fitting the doors with a horizontal brace it appears to me the door is too tall when compared to the photos. I dealt with this by removing part of the door track--the portion with the rivets but not the flange--which does not appear in the photos. I left the door hangers as is except I re-leaved the backside so the door would nestle up against the roof nicely. This leaves the doors sitting about 3-inches higher while also rendering a more accurate door tract IMO.