So i am having problems with the starter on my 67, and first off let me tell you that the previous owner pulled out the 326 and put in a 350 chevy and the block is a newer one 76-82 i believe

I found this out at orileys, when first asking for a 67 firebird starter and getting one where the bolts are parallel with each other the one i have are not in line, so after looking at the starter, it was deterimned it was a 350 chevy

Now after puttin one in arounf may, it really grind and whined during the end, took it back to orileys, still under warranty, worked great for about a month, now its starting to do the same. could it be the flywheel maybe?

Could be your flexplate. Inspect it for missing or damaged teeth.

Also starters sometimes (not always) need to be shimmed for proper clearance. Have you checked clearance to determine if shimming is needed?

There are also two types of Chevy 350 starters...different bolt lengths and nose lengths I believe. Maybe you still have the wrong type of starter for your engine...