Ron, the first 2 photos are of your new diff in my old 3rd member. it was a b!tch to get the original ring gear bolts out because they are lock-tight-ed AND torqued, but it is done, also, the ring gear doesn't wanna go easily onto the new diff carrier, it is almost a press-fit, so i just slowly tightened the bolts all the way around until it sucked it up.
about ring gear mesh with pinion after carrier swap: let me start by saying the guy who designed these and most 3rd members was a genius. the side-to-side position of the ring gear and diff carrier is adjustable by tightening and loosening the bearing retainer rings, so yes, the ring gear and pinion (which was not removed) fit just as well as stock when it was all said and done. the backlash was less than .03, but i don't have accurate measuring tools to get any closer than that.
the ring gear is indeed 7" across. i don't know what i was thinking before when i sadi i measured it at 6-3/8, maybe cuz the carrier was still in it and i couldn't get around it to measure properly. anyway, it's 7".
the splines match- BUT- i didn't check to see if the right side gear had the groove for the snap ring in the end of the inner axle shaft. the left (long side) shaft doesn't have a snap ring because it is retained by the 4 bolts holding the frame mount onto the housing. i will chack that tonight.
back to the genius of 3rd member drop out diffs- if you don't remove the pinion, there is no trouble setting the diff back up the way it was. it's just a beautiful operation.
ok, what else? ummmmmmm.....
oh, yeah- found some chipped side and spider gears, don't know how that happened, but there they are.
also, if someone wants, now that i have it out, i will weld this diff and you can buy it from me as a spool. not sure how much, but not too much, with core.
and gary- sorry, man, i don't have very good measuring tools, but i will try my best. if ARB has access to another Miata LSD, they can take measurments off it. might be easy to find in your neck of the woods. i will take some measurements, but like i said, they will be dull and less precise than they prolly should be for this sorta work.
