I have several of the Sequence IIIE test blocks, all brand new in the box. No paint markings at all on the blocks. All of them have the small hole in the front of the block, just like the ones for sale here. All blocks were given serial numbers and the part number BX-380-2. All manufactured by Bowden Manufacturing in Ohio, who produced them under contract with GM. If these are some of the IIIE test blocks, they cost 3 times the amount of a regular production block to manufacture according to the production manager at Bowden. I have alot of information on the Sequence IIIE engines and the parts used, both from the manufacturer and Southwest Research Institute where they were built and used.