I have a 1936 GMC and there was a zerk fitting on the UJBC as well, I replaced it with pipe plug.  Don't have an answer as to way since your correct that grease is not to be pumped in.

The previous owner might have lost the original plug and just replaced it with the zerk fitting (using it as a plug) because the threads are the same: 1/8NPT.

Dean

I believe a heavy oil like 600w was recommended and the early grease guns were able to use it so it made it easy. Until someone not knowing about the heavy oil puts grease into it.

Dave

My 1936 Truck has grease Zerks in places where gear oil is recommended. I don't think they have been replaced. Corn Head Grease from a Farm store like Tractor Supply is also a good choice for steering gears and U-Joint cavities.

Mike

So do I need to take the housing apart to get the grease out and replace with Gear oil ?

@david-dunton 

Dave is right.

Early "grease" guns would and did handle oil.

In fact, if I remember right early Chevs (my '29 for example) specifically said NOT to use grease at most chassis lubrication points, but to use 600W oil.

For that reason, the same fitting was used on the universal joint housing.

I don't know for a fact but I suspect the reason was that chassis grease of that era wasn't flowable and would cavity out, leaving the wear surfaces unlubricated.

I read somewhere that it was used at the factory to fill the bell cover and U-joint with transmission oil till the area would fill with transmission oil when the car is operating. When replacing transmission or torque tube, you could use it to fill with oil. This will take some time if you are pouring 600W thru a tiny funnel.

I have an oil squirt can that I use to squirt Mobil 600W into the tiny hole of the u-joint housing.

To measure the oil level in the u-joint area, I made a tiny dipstick using the steel stiffener strip that came from a modern windshield wiper blade. I figure when I put that dipstick in that hole, push it to the bottom of the housing, and pull it up again,  if 3/4" or 1" of the stick has oil on it, there's enough oil in the u-joint area.

For the steering box, I use a mixture of 2/3 John Deere Corn Head grease with 1/3 600W for extra flow ability. I use a plastic ear syringe from a drug store to suck in the Corn Head Grease and squirt it into the 1/8NPT hole in the steering box housing. First I squirt in a full syringe of grease, then a 1/2 filled syringe of 600W. I figure the gear action inside the steering box will mix the two.

Cheers, Dean

@rustoholic I’ve got a trigger oil can that I’ll try to put 600w gear oil into it. thanks