Is there a difference between a factory posi and dealer installed posi for 1969?

[sdkar]

If I opened the differential cover, would there be a noticeable difference?  If so, can someone post a pic showing this.  If it was a dealer installed posi, which is what I am pretty sure I have, what "brand" would it be?  (dana, eaton, etc.).  What did GM give you over the parts counter for this upgrade?  Any other info that would be helpful in this would be great. 

I currently have an original PG rear in my 69, but with a posi in it.  I have what also looks to a lightly tapped "D" under and offset from the axle stamping, and wondering if that means anything, or might just be a dink on the tube that looks kinda sorta like a stamping.

[69Z28-RS]

What is it coded for?   The code will tell you if it were a positraction from the factory.   if it were an Eaton it would have the 'E'... not sure what the 'D' means, but a check on CRG data should identify it

[sdkar]

My Camaro rear axle ID code shows it to be a non-posi.  However, my unit has positraction installed.  It is the factory numbers matching rear end, so I am sure that a positraction was added.  My question is, was a dealer installed posi unit the same as a factory or was it different?  What type of unit did GM sell over the counter and/or who was the manufacturer(s)?

[ZLP955]

Posi manufacturer codes (per CRG Drivetrain section) were:
D = Dana
E = Eaton
W = Warner

What's the casting number and date of the rear center? 'PG' was used as a rear axle code in all 3 years, open in 69 but posi in both 67 (10 bolt) and 68 (12 bolt). Could be from an earlier model?