starter noise

OK Jordan, it all depends on how you set up your midplate.....First it sounds like you didn't shim the flexplate back from the crank like it needs to be, bad on two counts, 1: it pulls the converter out of the front pump (VERY bad!), 2: it leaves the flexplate in a forward configuration so it won't clear the starter drive (that's why you shimed the starter forward). It sounds like you put the midplate behind the stock block proctector/starter locator plate, hence the need for the starter shim. Most aftermarket midplates are cut out around the starter mounting location and don't include thier thickness in the starter mounting equation, this works out very well if you use the (usually) supplied crank shim and place the midplate in front of the stock seperator plate as you MUST do, the converter MUST NOT be pulled out of the front pump any more than it's designed to be! So, this is the configuration you should have (starting from the front) block, midplate, stock seperator plate, bellhousing (with the same thickness shim as your midplate on the crankshaft between the crank flange and the flexplate). Now, I build all of my own midplates and I dont use the stock seperator plates, I locate the starter nose right in my plates. This takes the stock plates' thickness (and the need to shim the flexplate back the thickness of it) out of the crank shim equation.
So, to review.....Midplates are a good thing.
When you use a midplate you MUST move the converter back so it locates in the front pump as it was designed to do. (Either longer mounting bosses on the converter or a shim between the crank flange and the flexplate).
Just remember: as you move the bellhousing rearward the starter and the flexplate must follow it the same distance for proper front pump engagement.
So, to fix what you already have (from the sound of your post) put the midplate in front of the stock locator plate and the supplied shim between the crank flange and flexplate, do away with the started shim and you should be OK. Of course, any variations on this set-up and you'll have to do a little math to figure out what thicknesses you need where. Hope this helps. BTW, VERY nice truck!
Rob

Ok Jordan, thanks for the extra info. In the configuration that you have (with the converter with the long ears, which incidently is the way I like doing it because the more crank shim you use the more chance you have at shearing off the crank bolts and the flexplate loosing its register on the center hole support flange.....good for the fact of power transmition through the bellhousing area) the flexplate location hasn't moved fore or aft in relation with the block, therefore, if you use the stock seperator plate in FRONT of the midplate, it should locate the the starter in the correct location (make sure that the converter center hub still reaches and correctly registers in the pilot hole in the crank) negating the need for a starter shim. If you put the seperator plate on the BACK side of the midplate then you'll need a shim. If you machine a shim remember that it not only needs to be the correct thickness to match the midplate but it HAS to accurately locate on the machined ring on the starter snout. I've had customers leave the stock seperator plate out and wonder why thier starter makes noise and only lasts a week before the drive goes south. Hope this helps.
Rob