so i finaly got my 82 z 28 on jacks she is in bad shape but i was looking for tranny id codes to find out what i have and i got to looking at the flex plate a little close and it has some really bad cracks in it around the center ....... i started looking up what could cause that and i found some info not much saying that end play in the crank could cause flex plate/fly wheel to crack in the center..... not much more then that soo im planning on takeing the 305 out and rebuilding the whole motor any ideas on how i can fix that end play i want to put a flat taped edel brok cam in but im kinda afraid the block might be junk now any ideas?

I've never heard that one. The torque converter will float with the crank flange, so it doesn't make much sense. Loose bolts or misalignment are more likely. To your knowledge, has the transmission been out, rebuilt, or replaced? With the TH200C, that's pretty likely.

If you do have excessive crank end play, that's a function of the rear main bearing and crank. Doesn't require a complete rebuild, and it isn't likely that the block will be damaged.

five7kid is right i had a flexplate do the same thing on my 84, as i recall its fairly common especially if the car has let a hard life. i just replaced mine made sure the bellhousing and converter were installed and correctly never had another problem , you dont even HAVE to pull the tranny as i recall, but its been a while