[klondike98]

Tom, in case you haven't seen this Philco Service Bulletin #289, its very helpful in understanding the bakelite blocks. The "D" means the two caps are the same value and the "G" means the first lug of the block is grounded to the chassis. In your photo of cap #82, lug 1 appears to be grounded thus they scratched in the DG. This is consistent with the two 0.15uF caps labeled "82" in the schematic since both are grounded on one end.

I don't know why they would have initially marked the block DU, perhaps a manufacturing error.