The breather cap mated to the 0BA 6763 must be a specific fit too. The books show it needed to be fitted with 8BA 6766 breather cap. Stu

 

Length and angle looks almost like the filler tube used on the early N series Ford tractors. I don't remember the bracket attached, though. The 6763 number is shown in the tractor parts book as oil filler tube part and both the A and B variant listed. No, I do not have any tractors at this time to verify. That N series engine was used in some light commercial vehicles, panel vans in the early 1940s. I wonder if it could be for that obscure application. And like Ross mentioned, these engines were used in many industrial applications. I once owned an N series industrial engine that had powered a generator.

 

IMO, there's no A suffix, it was added by mistake. 6763 is the basic part number for an oil filler pipe.

6753 is the basic part number for an oil indicator boss gasket, road draft tube is basic part number 6758.

In the three parts catalogs I looked at (1948/56 Ford truck printed 1964, 1949/59 Ford car also printed 1964, 1953 Canadian Ford/Merc truck printed May 1953), the number is listed only as 0BA-6763

 

No dimple for the oil cap but it fits in the oil tube hole in the manifold. Does not fit into the draft tube hole.

JB

 

Bill's cited references, like mine, are for vehicles. I doubt that -a on your parts tag is a mirage. There has to be an industrial, marine, or some other goofball Ford reference that we don't have. Stu

Edit - thinking more on this, Ross speculated above that it could be for a military application that normal references might not cover. I've seen in my WW2 era wheel references that no military spec Dodge Power Wagon type wheels are listed. The same trucks were sold to civilians after the war, at which time the wheels got catalogued. Stu

 

Possibly an in flight commode and evidence disposal unit. I think I had something similar in my first car back in the sixties.

 

Inflight commode was called a relief tube.