OK, I got the 6-cylinder pump out of the shed and my V8 pump out of the garage. The 6-cylinder pump has a stamp that looks like 0 4 9. The bottom of the characters is very light if there at all. The V8 pump took some very fine steel wool and I found a complete 8 with a possible character before it. The stamping is upside down when looking at it from the side. The pump in my car is too hard to read.
The location on both is on the engine side at about 10 o'clock. Set the pump in front of you with the pully facing you. Then look at the housing on the left side between the upper bolt hole in the cast iron housing and the top inlet.
I've heard that you need to turn the wheels to bleed the air out. I did that so long ago I can't remember much but I think I did it a couple times and didn't have a problem. To rebuild it, there are instructions in the Overhaul Manual or just take the 2 rear studs and 1 fitting out and the housing should come off. The cast piece has an O-ring and there are other gaskets where the studs are. I bought rebuild kits years ago from a parts vendor, I think they used to be around $12. Make sure the housing isn't distorted (it needs to be round) or it will leak.
I hope this helps.