Ordered a block heater from www.autoanything.com. When it came I successfully removed the old plug from the block, but the new one I got would not thread in, it was too small. It doesn't seem to be after-market, the box it came in said Mercedes-Benz of America, etc. Don't know if it's just a parts mixup or if anyone else has had this problem. Put the micrometer in the hole and it said 37 mm without the thread. The thread on the plug I got from autoanything seems to be standard, and the block seems to be metric. Has anyone else come across this? Has anyone successfully purchased one online from some other parts store? Any help would be appreciated.