pattern matching - Replace expression, but only "outside" of a function

I have a horrid expression, which is basically a sum of exponents with coefficients. Here's a taste:

What I want to do is to replace ks with another expression, but to do so only when ks appears outside an exponent. Alternatively, I want to preform this replacement, but keep the arguments of all exponents unchanged.

For example I want

SpecialReplace[(ks-foo*bar) Exp[ks^foo-bar],ks->Y]

to yield

(Y-foo*bar) Exp[ks^foo-bar]

How would I do that?

Answer

Use two rules in the replacement with a dummy rule to replace exponents with themselves.

Along the lines of.

(ks-foo*bar) Exp[ks^foo-bar] /. {x:Exp[___]->x, ks->Y}

So anything that is an exponent is 'caught' by the first rule and the kx replacement rule doesn't get a look in.