Suggest you check with St. John's Welding. Prices are good, their stuff lasts longer than anything else we've tried, and When I spoke to them the other day, they told me about some new things they're doing which sound pretty good.
Have used the Manchester Forced Feeder chains for several years. Will not put anything else in as a replacement. Be sure to get the larger 557 links will only be $50.00-75.00 more and chain will last longer. I have tried Plastic Slat chain from Harvest Systems with mixed results.