[70oldsW30]

I have stripped the wiring out of a lot of Olds and I don't recall another ground strap besides the one that you mention. My '71 had an original pigtail lead from the negative battery post to the core support but there is none on the '70's that I have. I certainly don't recall anything to the frame. I don't think that the frame will have much need of grounding since there isn't much in the way of electrical devices mounted to it. I guess that the metering block switch for the brake light is down there, isn't it? But it will probably ground through the brake lines to the master cylinder and firewall. Anyway, that's what I remember.