Unless you have a panel-body 3100 Chevrolet truck, there was a slight turn-down towards the road at the end of the tailpipe, out the rear, under the bumper. The panel-body trucks' (at least the Suburban's) tailpipes "dumped" behind the driver's side rear tire. I think jorb has posted a link to a scan from the Factory Assembly Manual. If someone finds that post, please copy the URL/link into this thread.
I think the rear bumper on a pickup was optional, but the end of the tail pipe could not interfere with the optional rear bumper. I do not know if the end of the tail pipe was behind the bumper or under the rear edge of bumper.
