Last year Tiger Models said they would have several versions available by the time of the AMPS nationals. Do a search on the modern discussion board at missing-lynx.com. You should be able to find their post about the Stryker. HTH
look for USMC LAV-25 models. Vehicle is the same, with minor variations. Think Italeri makes several variants (TOW, command, etc.) that would be more than easy to convert.
Actually, the Stryker only looks simmilar to a LAV-25. The LAV Gen III that the Stryker is based on is longer, wider, and higher than a LAV-25. It also has different angles to it. Different tires/wheels, etc.etc. They are not that close. That is why no one has come out witha simple conversion set to convert a LAV-25 into a Stryker. Sorry, it is not that easy.