To my knowledge there are no official sources of SketchUp models. Your only chance is someone like Blake who might have done it themselves.
A little bit of background on why what you're asking is an issue:
Basically all modern CAD software uses either polygonal meshes or
NURBS for how it models solids. It's a bit like vector versus raster graphics, if you're familiar with that. You can convert NURBS surfaces to mesh but the other way is more difficult (well, actually pretty much impossible). NURBS to mesh isn't really any issue with most software that uses NURBS (like Creo, Solidworks, or Inventor)-- in fact, this is what anyone who designs in one of those programs for a 3D printer is doing every time they convert to STL (stereolithography) format and sent that to the printer's software-- but presents an issue to SketchUp, which deals in a format literally nothing else uses and last time I checked doesn't have any sort of control on its export to DWG (which is just about the only "nice" format it deals in last I looked).
The upside to this is that you might be able to use a Creo, Solidworks, or Inventor to convert to a format SketchUp is friendly with and use that. You'd probably either have to do everything individually or try doing the entire model at once and risk some inaccuracies. If you have the Pro version you can import DWG or DXF format, and any of the big three can export to that.
I'm sorry I couldn't be more help, but I tend to avoid SketchUp. Best of luck finding your models! In the worst case, you can use the field drawings to recreate the elements in SketchUp.