It's a TRS drive, it has the smaller lower. TR drive was used on big slow boats and has a much larger prop. Inside the boat will be the dip stick for the drive lube reservoir, that is where you check the level. Also a transmission, no shifting in the drive. That trans could be Mercury Marine or Borg-Warner. Drives for Borg-Warner will have a splined u-joint shaft like the newer drives, Mercury Marine will have u-joint shaft with internal splines and a big spring on the end. The tranny will have it's own dip stick. ATF
The vent plug you see on the upper is used just like the newer drives. The drain/fill plug will be port side near the front. It's possible yours is covered by the nose cone someone added. This was pretty common with a nose cone back then. If that's the case, ask and I tell tell how to change lube. If the drive lube dip stick in the boat shows empty --- stop --- because there is a special procedure to fill these.
Yes you can install a trim tab anode that's missing. If it will hit the prop we would just use a hacksaw to notch the tab.
An Alpha or Bravo drive won't fit on this transom plate.
These drives changed rotation by moving the driven gear in the lower from in front of the pinion gear to behind it. So if this is a new to you boat, you need to make sure someone hasn't put the wrong prop or lower on and used the trans for rotation change. The tranny don't last long when that happens.
Drive appears to be between 1977 and 1993 when the Bravo replaced it.
You can see the water pick up just to starboard on the transom.
They were a very strong drive for their time. But most of us that worked on them are retired by now.
