Jeff,
Modifying a 45 extractor may be more work than it is worth. The 45 extractor has two pads mid-length down the extractor. The 9/38/40 extractor only uses one on the outside of the extractor. The dimensions approaching the hook end of the extractor are are also different. If you do not make the modification correctly the extractor will not work correctly. I would suggest investing in a 9/38/40 extractor.
Modifying a 45 extractor may be more work than it is worth. The 45 extractor has two pads mid-length down the extractor. The 9/38/40 extractor only uses one on the outside of the extractor. The dimensions approaching the hook end of the extractor are are also different. If you do not make the modification correctly the extractor will not work correctly. I would suggest investing in a 9/38/40 extractor.