350 bearings questions

1973 K10, with a 350 V8.
Doing a Holley FI setup, headers, belt system
Motor is still in the truck, and I'm replacing the stock oil pan, with a winged pan, and one piece Oil pan gasket...
I have next to no history on this motor, except the truck was owned by one family since new, and they have all passed now.
I've owned it almost 18 years, ODO shows 56,000 miles, prob 30,000 in my care, but no idea how many time around that is.
I was told it was rebuilt, but no info if its the original, or a replacement.
Ran well with good oil pressure...

So I thought while the pan was off, Id pull a main and rod cap and see whats what..
Its a 4 bolt main which is correct for the 350 in 1973.

Main bearing looked ok, just some fine marks, but I popped the bearing off the cap to see what size it is.
Baffled now.
Main bearing says...
D.A.B. 86
8201 CAP L
3-39 A
4-39 DA 49

No idea what that means for size... and a good internet search gave me no info.

Pulled a Rod cap...
Again, bearing and journal look OK, with fine scratches, nothing serious.
Pulled the bearing from the rod cap, and the marking are:
D.A.B. 51
7555 CAP
6-30 C1
6-30 DA-41

Anyone enlighten me on how to read these markings?

Google:

"Bearing D.A.B. 86 8201 CAP L 3-39 A 4-39 DA 49" refers to a specific engine bearing, likely a "main bearing cap" for a particular engine model, where:

• D.A.B. 86 8201:
  This is the part number for the bearing, identifying it within the manufacturer's catalog.
• CAP L:
  Indicates that this is a "cap" bearing, meaning it's the top half of the bearing that secures onto the engine block.
• 
  
• 3-39 A 4-39 DA 49:
  These are likely dimensional codes related to the bearing's size and specifications, such as its diameter and width.

Key points about this bearing:

• Location:
  This bearing is most likely a main bearing cap, located on the crankshaft of an engine.
• 
  
• Function:
  The cap holds the lower half of the main bearing in place, allowing the crankshaft to rotate smoothly within the engine block.
  
  
• 
  
• Identifying the engine:
  To accurately determine which engine this bearing fits, you would need to cross-reference the part number "D.A.B. 86 8201" with the manufacturer's parts catalog.

Click to expand...

Got calipers?

Yes.
I have Google as well...

I have a big array of measuring tools, as Ive rebuilt motors and done machining before.
Can measure the crank rod journals, in place, but not the mains.
Have Micrometers, bore gauges etc, but no ball end micrometers, but Im sure I can improvise to check the bearing shell thickness...
But I was hoping someone could decipher the DAB bearing stamps...

If they're not factory sized bearings, any reputable shop that oversized the rods/main caps or undersized the crank would have marked them as such. I would also think there'd be some sort of .010 or similar notation in the bearing.

Plastigage? I think all of those bearings can be measured with plastigage. I don't know, though, especially with it being oily.

Platigage won't tell you if the bearings are standard .010 etc. It will tell you if clearances are correct. When you resize a rod or line hone a block we always took a tiny bit off the cap mating surface,now the bores are football shaped,then hone them out to standard round bore diamensions,never see or hear of anyone doing it other than back to std. O.D. you can measure your rod journals,as you already stated,if the rods are standard I would bet you money, the mains are standard. If you by new bearings buy 1 standard main shell,compare the thickness at the side of the shell not center of the shell with your old shell. Then it becomes a math problem. Post back if you need help. As for those stamping I have no clue,sorry. Use your micrometers,not calipers.