Originally Posted by
EjustE
Schwinn-Approved GT 500 is a long cage RD and that GT-510 will likely not be able to shift into the bigger cog nicely, because it is short cage.
If I were you, I would get one of
these (brand new for $7.26+ shipping) and call it a day. It will work better than any entry level old used RD, but you would need to adjust it to go only 5 gears. The aesthetics are not there, but....
Hell yeah, thanks! That price fits right in the budget of this project. I'm actually moving along a lot better than I could have hoped: For a bike that hasn't been touched in years, the bearings are all still good (but dry; thankfully it hasn't been ridden), and nothing has been stuck that bad (save the races, but thats to be expected)