Lakeview

New member here and looking for help. I have posted this question on other boards without a clear conclusion. Maybe someone here can help. I rebuild salvage vehicles and trade in some Silverado trucks. I have a 2012 1500 4.8, 2wd that I need a transmission for. I'm not keeping the truck so I don't won't to invest big money in rebuilding it. Supposedly it has a rebuild from Aamco in it now. It was making a nasty ticking noise and I think now the front pump or converter is gone according to a transmission friend. Interchange for junkyard parts show either a 2CBD or 2LPD code that I cannot find out what they mean. Trans in truck is missing the label due to the rebuild or I just can't get a picture of it. I have called the dealer and all they can tell is it is an M30 4L60e. This truck has the D321 shift pattern. I also think a 4.3 transmission will possibly work but not sure. Can anyone here shed any light on this subject? I am just looking for a good used transmission but I would like to buy the correct piece. Thanks.