1969 GMC VIn ?

[Wildbillvette]

Hello I am thinking about buying a 1969 GMC LB with 396, TH400, P/S, P/B, A/C. IT seems to be all original but there are a few things that don't make sense. The Vin Number CE10D-SA14XXX, does not match any of the VIN decoders that I can find. Could it be that it is different because it is a GMC?
The Letters in it D, S and A do not match the decoders that I can find. Also the Stamp on the engine pad is good T0918YP but there is no VIN number there. Is this normal? I thought that All Chevys of this era had a partial VIN number stamped there? I looked on the pad above the Timing cover and also on the vertical surface next to the oil filter and did not find one there either.
The Cylinder head has a date of I-12-8 and the block H-12-8 so that seems ok. The Head casting number is 3933148 which is ok to. I could not read the Block casting number. Should there be a Vin stamped on the transmission? If so where? I found a stamped steel tag rivited to the rt side that reads CJ-69-3126 263. Can anyone decode this tag?
Thanks in advance
Bill