Hippos are the only drop-in that I know of. Someone posted they are "great" whatever that means. Not much of a description. So I thought "what the hell" I'll be the guinea pig and buy a pair. Because they are from OZ it was a total fail. First I tried a credit card. But my bank cancels all Visa purchases in Asia because of heavy fraud. Then I tried my paypal account. PayPal insisted on trying to access my credit card as a debit card and natch it failed. I talked to them several times and the nice Indian fellow gave me instructions to fix the problem but the pages he told me to go to didn't even exist. And finally I just sent Puretone a bank check. Puretone sent it back saying that it would cost them more to cash it than it was worth.
So all I know is they do fit the SX without mods, they are a decent price, and they supposedly are "great". But someone else will have to be the guinea pig. I give up.
By the way given the huge price difference between SX and LEJ I'm wondering what your opinion is of the comparison? I had been gassing for an LEJ 6 or steve Bailey for a long time, but the high cost backed me off, especially since I had no idea if the jazz bass 6er thing made sense. But now that I've had the SX for a while I feel I can better justify a high end (heh, actually Low end) version.