Engine bolt hole identification help

[ThePoose 37]

Cleaning up the block for paint and noticed a couple of bolt holes that don't seem to go with anything.  #1 and #2 are coolant drain plugs I think.  There's something in the bottoms of the holes that may have once been plugs, but before I start drilling out, I wanted to make sure.  And if they are plugs, the purist in me wants to know if they should be the recessed hex type or the square head type.  #3 didn't seem to be used but maybe a grounding strap? As always, thanks for the help.

Driver side

Passenger side

 

[Brian Conway 264]

Well it' not an FE 428 or 390 block.

[bigmal 225]

I'm not sure if this helps but it is the best photo I have of this part of my engine (351C)

[ThePoose 37]

Oops. Forgot the 351W part. Nope, definitely not a big block. 

[RPM 1,190]

#1 on my block isn't a thru hole, I use it for a ground. 

[Vicfreg 773]

I have a 351 W and will go down to the shop and take a look, post picture a little later.....

[Vicfreg 773]

My late 1969 351W.  Rear of engine is to the left.   Front hole is water jacket drain, with plug.   Rear hole near starter is a dead-end casting hole of some sort. I dis-assembled the block, and had it tanked, etc.  So, I am sure that the rear hole is a blank.   

[Vicfreg 773]

Oh, your number 2 is the front one, number 3 is the rear one.

[Vicfreg 773]

Your number 1 is also a water jacket drain.  My best picture attached, had to crawl under the engine test stand....

 

[ThePoose 37]

Great.  Thank you.