You definitely have the wrong one Dan. Here's a link to a thread you already subscribed to. The picture of the one painted red is what you need.
http://67-72chevytrucks.com/vboard/s....php?p=5491809
One of these may still be for sale.
http://67-72chevytrucks.com/vboard/s...d.php?t=521538
I also saw a post where teeitup (Randy) states that he has a bunch of them.
Here's a not so good picture of mine. It also shows placement, but I have a TH400. The TH350 may use other mounting holes.