On my 46 pickup I have the original bellhousing that has the mount for master cyl (3 hole boss) cast from the factory. Had to grind a bit off the side of my S10 T-5 trans and also the factory master bracket. To mount the later trans to your 46 bell housing you'll need an adaptor to get from the tiny stock trans pattern to the later. If you've tossed the original bell housing you well then need to fab something else.
Best of luck
