I was fortunate to have the opportunity to acquire an original (not a CD or photocopy) 1966 flight manual for the B-52 B, C, and D models.
Its in great shape for a 50 year old document.
The manual contains a table comparing the key differences between models, from A thru H (as of 1966).
I thought that fellow WIXers might find the table interesting, so here it is:

Anyone restoring a B-52(!), let me know and I'm happy to loan it out!
Or I'm happy to look up any information that might be helpful, just reach out.
Other photos of the manual are here:
https://aeroantique.com/products/b-52-b-c-d-flight-manual-hard-copy-1966-usafIt should be good bedtime reading for several months....