Starting Problems-Dead 88

I have a 1988 88 that will not start. It seemed fine for awhile and for the last few days it have seemed to want to start slowly (i.e. like a dead battery). Today, I get nothing. There is not clicking (like a starter problem), the lights and all of the instruments light up okay but it is just dead when I turn the key over. Any suggestions?

80% bad starter motor
20% bad crank position sensor, cam position sensor, or ignition problems.

Check the positive battery terminal for corosion especialy the cable going to the starter.

my 87 (LG3) did the same thing, roll over real slow for about a week, slower each time. Meaning normally it goes cha cha vroom.....where it was chaaaa chaaaa chaaa chaaa vrrrraaaoom. Then it just seized up and would not start when there was 13V in the battery, changed starter solenoid, no difference, changed motor and started right up quicker than ever.

I have an 1983 Z38 that i put a GM crate 350 into, recently the ol' 700-r4 started acting up and one day while trying to start the car it sudden'y stopped turning and the force broke the starter housing. i replaced the starter and it won't crank the motor. I have the tranny removed because I am converting it to a 5 speed until i can afford a 6 speed. I was wondering why my motor won't turn. It wasn't low on oil or anything. It was running fine just the day before. I've had it do this before but not to the same extent. The engine would crank but it had a "rough" spot that it would slow through. And this only happens on cold/wet days.