The M890 iron/hybrid shaft is .370 (our code MA0312). What exact Maltby hybrid did you buy? The TC, the STh, the FDI and the M890 hybrids all take .370 tip shafts. The Maltby HiWay utility hybrid does take a .335 tip shaft.
If you know for sure you need the .370″, you can contact our customer service department and they can arrange an exchange of the M890 wood shaft that is .335 tip for the M890 iron/hybrid shaft that is .370 tip, if that is what you want.