GWR Macaw wagons. J diagrams.

Hi all.
In chasing all over the internet the Macaw wagon types, I see a common term, but have not found them yet. They reference the differing models by J Diagram ## {numbers) . ING4, at his great site had Macaws built to diagram J-4.
I have seen repeated reference to Macaw B's and D's built to Diagram J-19 for the re-enforced Tank carriers.
At I have located the only diagram drawing I have found, a J-50.
Please, is there a resource out there that shows these various referenced diagram plans??

Thank you in advance