Ok, here is what he have. When seperating the engine and tranny, the lower starter bolt broke off in bellhousing. The forces of God would not be enough to turn that bolt. So drilling was required. Engine:new. Started for the first time, and bendix would not disengage. It was only engaging about half way. I know this because when it finally blew, and I removed the starter, the bendix was flat on the front half. So I put another one in, and with in 6000 miles, I am on my 6th starter, and I am running out of money and patience. I redrilled the hole so it matched the flexplate(not original flexplate, but came off of a 302 just the same) with the top bolt in, I pulled the starter as far away from the ring gear as possible, and slid the lower bolt in, and tightened it down. Still grinding. I used a thin piece of aluminum as a shim and placed that between the starter and bellhousing oposite to the engine. Still grinding. What in the world would cause this problem? I don't think it is electrical. When I pop start it with the clutch, it still grinds. I don't have a typical starter switch, as my truck didn't have it when I got it. The original ignition switch on the steering column inside the dash, is always in the on position. I have a switch which cuts power to the original switch. and I have a sprung starter switch that only works when the ignition switch is on, and when the clutch is depressed, so please? how do I fix this problem? I have too much money and time in this thing to throw it away. Thankyou, sorry for the length

 

Are the fly wheel and starter the correct matches for this vehicle? Have you verified this? If so, then are the teeth of the flywheel O.K.? Since you've had the motor & tranny out, I'm going to bet that it's an alignment issue. The gears aren't meshing parallel or the depth is wrong. You've replaced the starter, right? So it's not the problem. Try taking a set of depth micrometers, or a dial caliper's depth rod and precisely measure the depth to the face of the fly wheels teeth from the machined boss that the starter rests on. Measure from the extreme farthest points and note the difference, & prepare to shim it straight. Are the dowel pins still in the tranny- engine holes? Did you
seat them securely before tightening the bolts that join them? Carefully examine fly wheel teeth for burs and dings, too.

 

PS. Take a dial indicator to the fly wheel's ring gear and see if there is any runout. When your bendix hung up something could've come loose, or bent.