Let’s be aware of undercoated cars and non undercoated cars from the factory. The non undercoated cars still had the 4 wheel wells and underneath the front fenders done.
Then we have undercoating done at the dealership. This is where you see it at different places on different cars and can cloud the discussion of what was factory sprayed or not.
There is no factory undercoating on the seat studs and nuts. There is a tape outline on the floor covering the seat holes. The seats were one of the last things to go in the car. After the car was running and driving.
No factory undercoating on any of the front suspension, engine/trans/exhaust/trans crossmember, leaf springs/hangers/shackles or rear axle and brake cables. Not on the car yet.
Fuel tank, fuel lines, brake lines, and the bolt on dual exhaust bracket were on the car when undercoated. Also all body panels and bumpers were on the car. Along with wheel well and rocker mouldings.
I should clarify that my observations come from 67-70 B-bodies from St Louis and Lynch Road plants.
One thing to consider. When the body "drop" happened, the engine and transmission, on the K-frame, driveshaft and read diff and springs was below as an assembly. If the body had been fully under coated prior to this, there would be the chance that the undercoat could be sprayed at the transmission crossmember and rear spring hanger mount locations. This would be a big problem for installing the whole drivetrain, if undercoat was on these mounting points. The trans crossmember is a pretty snug fit, and undercoat at that spot would be a major issue. And there is no way they could have undercoat at the spring hangers surface and risk sandwiching undercoat in between.
Unless they used some sort of "mask" to protect these area from the undercoat.
As I mentioned, this car, and others I have restored, have undercoat on the rear spring hangers, and the black painted Trans crossmember is undercoated as well, which makes me believe the rear axle and springs assembly and engine, Trans and K frame was installed prior to full undercoat. Yet there is undercoating on the floor above the mufflers and driveshaft.
