Wagenboy,

I've got a 79 TD and I use Thule bars with rain gutter mounts. The gutters are extremely strong and you'll be able to put almost anything on your roof. I have the extra-wide bars on mine, and I often lug around a canoe and two mountain bikes on the bars. Even with this weight and drag, everything stays very secure, much more than if you were mounting on the TD roof rack. Thule bars for rain gutters are easy to find used, as rain gutters are obsolete on cars and people are getting rid of their gutter bars.

Denis