For what value of x, (37)^3x- (33)^3xcan end with either 1 or 2?

So here my assumption is that x is a whole number. 
- (37)^3x 
when x is odd, will end with 3. And when x is even it will end in 9.
And for the other, when x is odd it will be 7 and for even it will end with 9.

So for x being odd, the difference will be 4, And for x being even the difference will be 0.