@fangdang
To expain more fully: For having any chance of successfully flashing another device firmware there must be hardware compatibility. The conversions mentions above can be done because they have matching PCB P/Ns (See here: [Only registered and activated users can see links. ]). These are proven possible nuvi 2797 > dezl 7x0; nuvi 2460 > dezl 5x0 (but loses Voice Command); nuvi 2x5W (HWID 0827 only) > nuvi 465 (Retains BT only with 265W).

Unless you can find a dezl model with the same PCB P/N and same region layouts as Drive 51 it's simply not doable. Otherwise any attempts will likely result in bricking it.