In case you do not have the Culotta "Tank Cars" book, page 65 shows NDX 608 which appears to be like the ACOX 5259 Semet Solvay Div Allied Chemical one we discussed yesterday. This one is from Nitrogen Division, Allied Chemical and Dye Corporation. He says it was originally part of General Chemical fleet and describes it as lined tank, GA Type 30 underframe, blt 6-41. The image quality is poor but you can see the usual double row of rivets attaching the tank heads, whereas there was just the faintest suggestion of the rivets in the ACOX 5259 image . The dome arrangement and "straps" look like those on the ACOX car as do the bolsters and bolster ends. The horizontal "line" where the bottom tank course would be fastened to the upper just barely shows rivets in this low contrast NDX 608 reproduction (I could not make out any indication of rivets at that location on ACOX and had to use my imagination to make any out at the tank head). Thus it seems reasonable to conclude that the ACOX car is a Type 30 of similar vintage, that the lower seam on it is riveted (though only the edge of the lower tank course is visible) and that it is not insulated.
The ACOX 5259 image is an example where some Photoshop work could have made the book much more useful. But Culotta has provided a lot of raw and partially processed data so I should not quibble. Too bad his situation changed impacting his rail book productivity.