If you only need a mount and not the cradle, here is what you need.  This is the hinged cradle with standard Nuvi ball to fit the back of your car cradle.

Fits many Aera, Nuvi, Dezl, and StreetPilot models including:

AERA: 500, 510, 550, 560

DEZL: 560LMT, 560LT

NUVI: 30, 40, 40LM, 50, 50LM, 200, 200W, 205, 205W, 250, 250W, 255, 255W, 260, 260W, 265T, 265WT, 275T, 370, 360, 350, 310, 300, 465T, 500, 550, 680, 670, 660, 650, 610, 600, 785T, 775T, 770, 765T, 760, 755T, 750, 885T, 880, 860, 855, 850, 1100, 1100LM, 1200, 1250, 1260T, 1300, 1300LM, 1350, 1350T, 1350LMT, 1370T, 1390T, 1390LMT,1450, 1450LM, 1450T, 1450LMT, 1490T, 1490LMT, 1690, 1695, 2200, 2250, 2250LT, 2300, 1300LM, 2350M 2350LMT, 2350LT, 2360LMT, 2360LT,  2370LT, 2450, 2450LM, 2450LMT, 2460LMT, 2460LT, 2555LT, 2555LMT, 2595LMT, 3450, 3450LM, 3490LMT, 3550LM, 3590LMT, 3750, 3760T, 3760LMT, 3760T, 3790T, 3790LMT, 5000

Nuvi 42 42LM 44 44LM 52 52LM 54 54LM
Nuvi 2457LMT 2497LMT
Nuvi 2557LMT 2577LMT 2597LMT GPS

STREETPILOT: C310, C320, C330, C340, i2, i3, i5

Fits the following Zumo car cradles:  550, 500, 450, 400