Progress on the back side of the transom. (As the title says, this is a 725/Indy project.)
The transom casting is a VERY beefy unit; everything mounts to it. There is no inner transom shield, only a backing plate for the mounting studs. The installation pattern is an exact interchange with an NXT. The transom cutout, stud pattern, propshaft height and prop setback are identical.
On the rear, you'll notice that the bottom steering pivot pin is supported both inside and outside of the gimbal ring. This puts the pivot pin in double shear, to better handle the higher loads at the bottom. The ears in the lower corners are the forward mounting points for the integrated steering rams.
On the front side, the "Pi"-shaped casting carries intake ports on both sides for both the steering and trim. This allows the drive to be plumbed from either side, and allows simple interconnections with a minumum of fittings and connection points between drives in twin and triple installations. The transmission plugs directly into the center bore, and a pin is inserted through a clevis on the top of the transmission and through the mounting boss you see just above the bore. In plug-installations, this serves as the rear engine mount, so there are no rear engine mount alignment headaches to worry about. The entire transmission assembly seals to the transom casting, so any damage to the u-joint boot will NOT result in flooding the boat. Nice touch....