Most loader manufacturers made mounting kits for different brands of tractors, so the short answer is most of them. There are new loaders made today that can be fit to the Olivers, so finding one shouldn't be a problem. If you are looking to buy used, try to find one that was already on an Oliver tractor, preferably a 15xx or 16xx sized model.

Oliver had their own line of loaders, and they could be ordered with kits to mount them on other brands of tractors. The Oliver 1610 was a popular loader for that size of tractor, if you are looking for a loader to 'match' the tractor.