Your serial could have been misread,every PT series gun that ive seen has a ABC12345 format. Its very possible your dustcover is simply worn and hard to see.
As far as magazines go, check the FAQ for details on that. An interesting quirk that you may or may not care to know about, older PT92 magazines like what came with my PT99 wont work in the new guns, but 17 rounders made for newer generation Taurus weapons work in the old guns.
Good find, a very classic gun, and hope she shoots true for you!