Could you just mold up some new letters with epoxy, and whittle them with a Dremel? It could be easier than replacing an otherwise good tank. Coat of paint, no-one except you would know the difference. You could even patina the paint so it looked old-timey : )__PRESENT
We have a 1936 or 1937 rd4 complete and running cat with blade. Just email me at [email protected] if interested in the complete cat.