Most of you probably already know this but just in case, here's a little bit of helix info.
The 92 and 93/94 helixes are not interchangeable, there is a slight difference in the spline.
The 42/37 for a 92 has casting marks 8AX 38 and there is a small A die stamped on it.
The 42/37 for the 93/94 has the casting marks 8AX 38 with a small R die stamped on it.
The 43/37 is a Hauck cut helix, according to Hauck it was a more aggressive version of the 42/37, more of the 42 degree angle. The one that I purchased from Hauck was cut on a 39 degree helix and the ramps weren't replated. Not sure if there is enough material to recut any angle helix or not, i.e. if a 33 can be recut to a 49 but I'm sure a quick call to Hauck would answer that question.
I also purchased an unused 49/46/39 from a guy who apparently did testing for Yamaha back in the day. I thought it would be way too aggressive but it seems to work pretty good.
There was also a PSI Helix that was something like 47/44/39 for running with their quad pipes.
Ken