Starter differences for manual and auto?

[coyote72]

I have been working on my Grandpas '73 C20. One of the things on my list was to replace the starter. The bendex would not always come out and push the starter gear out so you would have to bump it a few times for it to grab. I picked up a replacement at our local Orilies auto parts store. The replacement appeared identical to the old one so I took it home and got it installed. Upon hitting the key, a god-awful gear/ cranking noise. I have played around with shims and even tried another 'new' replacement starter. Same deal. I am wondering if anyone knows if the starters are different for manual and automatic? The combo for our truck is 350/ SM-465 4 speed/ 2wd. Thanks