A method for preparing a crystalline molecular sieve selected from the group consisting of SSZ-13, SSZ-35 and SSZ-42 having a mole ratio greater than 15 of an oxide of a first tetravalent element to an oxide of a trivalent element, second tetravalent element which is different from said first tetravalent element or mixture thereof, said method comprising: A. forming an aqueous reaction mixture comprising a source of the oxide of the first tetravalent element; a source of the oxide of the trivalent element, second tetravalent element which is different from said first tetravalent element or mixture thereof; a source of alkali metal or alkaline earth metal; an organic structure directing agent capable of forming the molecular sieve, and an N,N,N-trialkyl benzyl quaternary ammonium cation; and B. maintaining said aqueous mixture under sufficient crystallization conditions until crystals are formed; wherein oxide is silicon oxide, germanium oxide, or mixtures thereof, and oxide is an oxide selected from aluminum oxide, gallium oxide, iron oxide, boron oxide, titanium oxide, and mixtures thereof; and wherein the reaction mixture has a composition in terms of mole ratios falling within the ranges shown below: YO 2 /X a O b 5 - infinity OH - /YO 2 0.10 - 1.0 Q/YO 2 0.05 - 0.50 M n+ /YO 2 0.05 - 0.30 H 2 O/YO 2 2 - 200 Q/(Q+M n+) 0.30 - 0.90 where Y is silicon, germanium or a mixture thereof, X is aluminum, boron, gallium, titanium, iron or mixtures thereof, a is 1 or 2, b is 2 when a is 1, b is 3 when a is 2, M is an alkali metal or alkaline earth metal, n is the valence of M, and Q is a mixture of an organic structure directing agent capable of forming the molecular sieve, and an N,N,N-trialkyl benzyl quaternary ammonium cation; wherein the mole ratio of the organic structure directing agent to the N,N,N-trialkyl benzyl quaternary ammonium cation is 1:4 to 4:1; wherein the N,N,N-trialkyl benzyl quaternary ammonium cation has the following structure: wherein R 1, R 2 and R 3 are each independently methyl or ethyl and wherein the cation is associated with an anion, A -, which is not detrimental to the formation of the molecular sieve; wherein the SDA has the following structure for preparing SSZ-13: wherein R 4, R 5 and R 6 are each methyl and wherein the cation is associated with an anion, A -, which is not detrimental to the formation of the molecular sieve; wherein the SDA has the following structure for preparing SSZ-35: and wherein the SDA has the following structure for preparing SSZ-42: wherein the anion (X -) associated with the cation is any anion which is not detrimental to the formation of the molecular sieve. A. forming an aqueous reaction mixture comprising a source of the oxide of the first tetravalent element; a source of the oxide of the trivalent element, second tetravalent element which is different from said first tetravalent element or mixture thereof; a source of alkali metal or alkaline earth metal; an organic structure directing agent capable of forming the molecular sieve, and an N,N,N-trialkyl benzyl quaternary ammonium cation; and B. maintaining said aqueous mixture under sufficient crystallization conditions until crystals are formed;