"D" prefixed serial number means that it is a 201 cubic inch (4.4" bore X 4.4" stroke) engine. Original type of engine for a 4600.
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The block was (most likely) cast March 7, 1979.
If you look at the other locations marked in the image below, you might find the assembly date for the engine.
![Hood Automotive tire Azure Motor vehicle Rectangle]()
You have oil leaking from the transmission and/or the engine and it ends up at the bottom of the bell housing. The drain hole is there to prevent leaking oil (and condensated water) to reach the clutch parts.
The cotter pin sits in the drain hole, to keep the hole free from debris as it wiggles around. This cleaning action is not that effective, depending on what environments the tractor meets. Especially not if the timing inspection cover on the right side, below the starter motor, is not secured in closed position.
You can use a piece of wire, or something like that, to poke around in the hole to check that it is free from debris. This way you know you have the proper evacuation of liquid.
You need to split the tractor (unbolt the engine from the transmission, and pull them apart) in order to renew the leaking seal(s). Until the leak(s) is(are) fixed, always park the tractor slightly uphill to get rid of as much liquid as you can. The head of the cotter pin can be seen in this image:
![Automotive tire Automotive lighting Motor vehicle Rim Automotive wheel system]()
Ford Part Numbers, Casting Numbers, and Date Codes
If you look at the other locations marked in the image below, you might find the assembly date for the engine.
You have oil leaking from the transmission and/or the engine and it ends up at the bottom of the bell housing. The drain hole is there to prevent leaking oil (and condensated water) to reach the clutch parts.
The cotter pin sits in the drain hole, to keep the hole free from debris as it wiggles around. This cleaning action is not that effective, depending on what environments the tractor meets. Especially not if the timing inspection cover on the right side, below the starter motor, is not secured in closed position.
You can use a piece of wire, or something like that, to poke around in the hole to check that it is free from debris. This way you know you have the proper evacuation of liquid.
You need to split the tractor (unbolt the engine from the transmission, and pull them apart) in order to renew the leaking seal(s). Until the leak(s) is(are) fixed, always park the tractor slightly uphill to get rid of as much liquid as you can. The head of the cotter pin can be seen in this image:
