Tamraz sells on eBay quite a bit. I'm not sure how long they've had an actual website. I bought a bunch of stuff a few years ago for a camaro I had and at that time, Chevrolet was pretty much all they sold. Shipping was always quick and customer service was great. I ordered left and right torque boxes and was sent two lefts. They ended up sending me a right and told me to keep the left and do what I wanted with it!
I just ordered front and rear valances for my 70 dart for $340 shipped!
What sending unit? I bought a spectre OE replacement for my dart and it was HORRIBLE, no accuracy at all. I ended up repairing my original and reused it. I have the spectre one if you want it.