Technical drawings and history

[Kid_of_the_80s]

Just trying to resurrect an earlier 'closed' post of mine about, eg. the Class 50s, 33s, 37s and their ilk, and in particular the comment about "Are there any good books about the design and making of these now disused locos? I've seen train spotter books listing the numbers, or you sometimes see rambling historical things about what loco operated what service on what date, but I I'm thinking it would be interesting to read something of a cross between a history book and a Haynes car service manual. Something that might, for instance, say "... the engine was originally designed with [certain characteristics] but it was found that by changing [such and such] the range or fuel efficiency was improved ..." or "the early models had the cab made in [wherever] but an extension at the factory enabled them to be fabricated onsite using the then new technique of [.....]". A few cutaway drawings wouldn't go amiss either"

Any ideas please??
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PS. I had in fact rather forgotten about this site until it told me by evidently automated email that someone in China had tried on five or more unsuccessful occasions to hack my password!