I checked the partsbook and came up with this;
On 64 and 65s the manual box is bolted with three bolts w/washer part#6025677. The same for 1965.
For cars equipped with power steering there is no description at all!!
Hwever there is reference for 1965 C-body cars. The box on those cars should be mounted with one (1) bolt w/washer and two (2) studs! So my guess is that they didn't have any left so they added the C-body set-up instead! Comments?