I just bought a zerostart lower radiator hose that looks an awful lot like the one on dieselgiant site for about $35. I had to get on the Phillips and Temro website, the company that makes zerostart, and ask them where their suppliers were in my area. They wrote me back in an hour and directed me to a place 10 minutes from my house. Had to pay 9 bucks to have it UPS'd to their shop since they were out of stock, but it's a lot cheaper than $90. (Sorry, dieselgiant) On the other hand, I could have bought a Katz at the local Tractor Supply Co. store for $22. But I think, (my opinion here) zerostart makes better quality stuff, so I ordered theirs. Less than fifty bucks with the shipping. If they'd had them in stock, it would have been less than forty. Get the 1 1/2" model. The P&T site told me my 81 300D needed a model 3200003.
www.phillipsandtemro.com