I "think" the t-case is the same for '99 as it is for my '95. If that's the case, there are six (!) switches in there. I haven't plugged them in to a site for pricing, but I guess I'd try cleaning them before replacing them. I've never heard of an aftermarket replacement for them and they're probably Mitsubishi-specific.

Their sole function is for indicating lights, and, if your truck has a locker in the rear end, to keep you from locking it unless you are low range. The actual shifting is mechanical.

John B.