Your dimensions vary!?, but I think one of these will fit:
Switches - Rocker Switches are in stock at Digikey. Order Now! Switches ship same daywww.digikey.com
DigiKey only has the momentary, OFF-(ON), type in stock, but this one has the OFF-ON type:
Switch Rocker ON None OFF SPST Quick Connect Curved Rocker 20A 12VDC 250000Cycles Automotive Bulkwww.onlinecomponents.com
Measure carefully and compare to the dimensions in the datasheet.
Momentary ON, of course ==> OFF-(ON), sorry.
And Mouser Electronics