The 3100, 3600, 3800 all use the same cab/hood/fender/front sheet-metal and mounting hardware/points.
However, there was a change in how cabs mounted (between 47-55), but this can be dealt with.
If/when you get the "recipient" frame, let us know the year.
The 47-54/55 Factory Assembly Manual is actually a 54/55st FAM.
The wheelbase did not change in 1954, but the frame components changed in 1954.
