Help starter issue 84 s10 with 350 hei!! help!!?

i have a 84 s10 with a 350 hei in it. ever since having to replace the starter that was originally with the motor ive been thru living starter hell fiasco! the original worked well for several months and begun to grind a little and it got worse and worse slowly then it was time to replace, just old age. having replaced the starter with the same brand and model p6416s i found that upon initial installation and without shims the starter purred like a kitten and hit the lick every time. but this only lasts a few days then it gets to just grindin and leavin me stranded (350 turbo auto) the grinding is leaving only very abrasive marks on the flywheel so therefore the ring gear must be too far away from the flywheel but it still manages to bind up somtimes. i put washers below the head of the starter bolts in an attempt to bring the ring gear up higher to make better contact which at first works ok at first but only for a few starts. ive shimmed it every way possible twice even if i knew it to be wrong just to be sure but with no success.i started thinking if the gear is getting binded but the starter is too far away then the starter must be at an angle or something. sometimes when i tighten the starter back up it will have a little play, but not always. i finally noticed that the starter is on top of part of the s10 frame and the starter MAY not be resting where it should because of about 1/32 inch of metal frame. the way it rests MAY cock the starter slightly to the side but very little, also it MAY be pushing the starter away from the flywheel as well. im considering taking a metal file to the points of contact with the starter but its too close to call if the frame is actually interfering with the starters intended resting place, but as of right now, ive exhausted all other options. i use the diagonal starter bolt holes but theree is another threaded hole in the block which might be for a straight mount starter? ive went thru 6 starters now in the last month, somebody please give me a lead or suggestion, ANYTHING! i know this isnt the first time a 350 hei has been put in a 84 s10 so somebody should know something out there! lol