Recently, we had a thread where this issue was discussed at some length. If you look for it, you will easily find it.
There are two OEM cabs for the 400 Series. The first one was the J-2 and the later one was the K-2.
It appears that the K-2 was introduced right at the time when the wheelbase of the 400's was lengthened by 2 inches.
Older 442, 444 and 446 models all had a 46" WB and measured 13 inches along the checker plate floor between the dash tower and the seat base.
Later 444, 446 and all 448 models measure 15" in this location and had a 48" wheelbase.
The fact that the footrests connect to the fenders has no bearing on the fit of the cab. The issue was always the two inch WB increase. It is my understanding from the recent thread that the cab will fit both wheelbases. If someone else has a different understanding, then now is the time to speak up.