So, I'm looking to replace the original rear derailleur that's on my 1989 Schwinn World Sport. The one that's on there now is the SunTour 3040 AccuShift rear derailleur.

On the bike I have a 6-speed freewheel (14, 15, 17, 20, 24, 28T). The rear shifter is indexed (an old stem mounted SunTour 3040 AccuShift shifter) and on the crankset the chain rings are 40 and 52T.

For front derailleur, on the bike I have a Shimano Sora FD-3400 double (the stem mount shifter for the front derailleur is non-indexed).

With that info, can anyone point me in the direction of a compatible rear derailleur? I'm not really looking to spend more than 30 bucks.

All the help is much appreciated. Thanks guys and gals!