judging by that everything looks perfect,
it's perfectly normal that you can stop any one wheel with a diff more or less effortlessly; you just should try to stop both, since then you'll have the engine working against you
wonder if i can weld it solid...... hmmm...
you can, you shouldn't!
As mentioned, these things get rare..
if it breaks, clean the parts and sell them, get a 1" live axle and use that instead of a differential.
....
Ill take a trip to the hardware store and pick up a saftey clip and reassemble it. Also pack a bunch of grease in it and on the shafts.
I believe that the previous owner had tinkered with it because one of the brackets holding the axle was missing a bolt.
If its just missing the clip, then i'll get off really really cheap! lol.. fingers crossed!
perfect!
clean fresh grease if always a good thing
I think i might have taken the differntial apart for nothing... well i guess it doesnt hurt that i filled it up with grease.. but it looks like im missing the little square metal block that fits inbetween the shaft and gear..

well.. yes some keystock might help here

But that's okay, just a small part
http://www.bmikarts.com/search.asp?keyword=keystock
(I don't know the size you need)
But I'm sure you'll find it in almost any hardwarestore as well, it costs next to nothing, so you can even buy a variety of sizes to test if you can't measure correctly what you need.
As for the bolt (which isn't a bolt but a set screw that goes in there)
my best guess is it's a 3/16th (it should only prevent the keystock to fall out, no big force needed)
but you should take the sprocket of and see what fits in right in the hardwarestore
'sid