The 70-300 LD is a real diamond in the rough, it's supposed to be an entry level macro/telephoto and well, you can see the results.
There are several copies, Promaster (the brand name printed on this lens), Quantaray, Sigma, but it's the exact same thing as the Tamron LD, same design, same elements. They are all the same lens. It is made for nearly every autofocus camera on the market. Same low dispersion elements. You can find them for as low as 50 bucks, this copy came with the Maxxum in a pawn shop with another lens and bag for 50 dollars.
I have an incredible Sigma 1:1 Macro I'll have to dig out... I think my Tamron macro fits my screw mounts. The Sigma has a K-mount though, and rarely gets used as the OM is my fave 35mm, but I think I will dig it out and play with it over the holidays.