I suggested as much back in post #19.I don't see what the body shop guys have to gain by refusing to tell you where your car is. I would think they want you to come pick it up and pay them something and get it out of their way. Honestly, I hate to be the bearer of bad news, but I think your car is gone.
This is a long thread so maybe I overlooked it, but I've not seen where anyone has actually laid eyeballs on your car, The police detective says he was told it's in storage, but he's not seen it.
They are stalling, stonewalling, and delaying you to set the stage for claiming they sold it to cover unpaid storage fees.
Also I didnt see where it was mentioned how long the Elco has been in the possession ot the body guys. Has it been 9 months or 5 years. Body shops are well known for this type of activity. If one takes their classic to a body shop then stay on top of it. Make unannounced visits every few weeks. If things are stalled then ask why and start making alternate plans. I pulled my 69 out of a shop after 8 months because there was little to nothing being done, but ill bet I made a half dozen visits in that 8 months and to be honest I should have pulled it after 4 months.
Best suggestion of all is to learn to do the work yourself. Then you will have total control.