[P.S.]

I can answer that.

If you flip your Hemmings Model A calendar back to July 2017, you will see a very professional picture of my all original 29 standard fordor. It drives like a dream; Easily the best driving Model A I have ever driven.

It does have new wheel bearings, rear end bearings, generator bearings, clutch, tires, fan belt, radiator hoses, motor mount rubber pads, and new oil and gas. Can I still call it "all original"? You bet. You see, those items are maintenance items. If your plan is to park the car and never drive it, then you don't need to replace those items. Might as well just take a picture of the car and hang it on the wall if you're going to do that.

Our all-original car is still very much alive. It still has all of the parts it left the factory with, including its factory applied paint job. The seats still have the factory material and stuffing (but I keep them covered with blankets to prevent tears), the frame and undercarriage has been kept clean all its life just like the topsides, and the car has never been taken apart. All the main bolts and hardware are still exactly where the factory workers left them. Pretty sure that qualifies as an all-original car by almost every definition.

So, where do you draw the line on originality being lost? That is highly subjective! My personal opinion:

When you remove the body
When you do a repaint.
When you replace any interior cloth
When you change the motor
When you swap any part, like the rear end, with a part from another car
When you "modify" the car (high compression head, overdrive, etc.)

Opinions will vary.