Dudley,
Yes. Most times you will find draw marks in the cross and sub rails. So, that means you will need to be careful to preserve them during your finishing of the metal. I'm a bit fanatical and wouldn't actually recommend people spending their time this way. But, after initial sandblasting of the rails, I applied a thin coat of primer to preserve from rusting. Then, if and when I had to fill pits anywhere near the draw marks, I always protected them by masking. This leads to having to feather the layers before your final primer and finish paint. The real key to preserving production marks is to keep your materials thin. The factory sure didn't apply much paint, neither should we. But, again, my methods tend to take an awful lot of time and in the end, only you can decide if it would be worth it. I like crawling under cars where the restoers' took the time to do this. It just makes the metal look almost like assembly line. I say almost, because as many know, the factory finish on the undersides of the bodies is nowhere near how we restore them.
In response to your second question, yes and no. I've seen some original cars brownish primer under the bodies, and also have seen the primer with a bit of body color. I have also seen just some body color and no eveidence of primer. I have not yet seen an original Model A with a full coat of paint covering all of the underside of a body. I think this is due to different production lines having different practices, and other similar reasons.
Just opinions.
Dave Lopes
