I am new to the forum and have recently purchased a 69 Camaro RS. Ironically, I have been trying to decode all of the #'s on this car and started with the rear end. One of the #'s on my rear end is BG0219G2 with an E under it. From the research I have done, if it is a posi trac it will have a letter under the sequence of #'s. The E on mine stands for Eaton. If it was a D it would stand for Dana, etc. The forst two letters I am not sure of. The next four #'s is for the date produced, ie 0219 is for Feb 19. The G is for Cevrolet Gear & Axle and the last # is for the shift. In my case it would be the 2nd shift. Check out the rear end section of the CRG website and it may help you out.