Hey 223,
I started out doing that, and really should continue. The drawing sometimes helps to more fully understand the individual parts and their relationship to each other. And it's enjoyable. And I could end up with a pretty nice set of drawings. In the back of my mind there's a neat way to tie the 3D and drawings together - book, CD, website, don't know yet.
As a resource, I'm using the K-36 drawings available from livesteamlocomotives.com, and a few from the DPL collection. I don't think DeGloyer has any K-36 material. These are drawings done by the D&RGW engineering department in 1926 or shortly thereafter. Some from DPL are marked as obsolete, usually listing a "superceded by" number. One drawing of the water column is marked that way but I can't see what may be different in comparing to current photos.
Slight changes have taken place over the years, as well as differences like pilots and running board steps. There's a device on the pedestal binders that's not depicted in the original drawings. Carlos has a picture of an engine truck radius bar showing the same pattern number as in the engineering drawing, and Roger has one from 489 showing a different number. There are probably slight differences within the class as delivered by Baldwin as well.
As you might expect, there are a lot of holes as to available drawings, and making my own in an effort to fill the gaps could be most rewarding. Ash pan and under-cab support (besides the rear footplate, got that) spring to mind.
Any drawings I may do, same with the 3d model, would most likely be a generic representation of the class as a whole, rather than a specific number.
Mike