Ok here is the situation. Originally I bought a tassajara gary fisher on ebay for pretty cheap a while back. I have since upgraded to different wheels and some other components on the bike. I decided about a year ago to start learning how to repair bikes on my own since I also have an older schwinn moab that could also eventually be fixed up. Anyhow, eventually I broke the crank set's middle cog (bent a tooth and made a gouge in the cog). At first I thought that I could replace just the cog but it turned out that the cogs are welded together on the original crank set.
I looked into buying a full crank set and found a deore shimano crank set(octalink splined) with bb(bottom bracket) for very cheap on ebay. Anyway, before I did all the homework that I should have and had installed the sucker, I realized that it was the wrong size bb. I realized this when riding, the crank arms would tighten to the point where I could no longer pedal, so I knew something was wrong. I compared to the original square tapered bb and noticed that the octalink was much shorter. After getting a second new bb from my LBS (the first one they gave me was isis rather than octalink) I thought I finally had a good fit, until I started to notice a wobble to the whole thing. Basically, there is a slight wobble so when pressure is put on one side or the other there is a little "play" in it.
So, I am under the impression that I need a spacer to correct this wobble. I am wondering what size spacer, and which side it goes, cup or non-cup. I am posting some pictures to illustrate my situation, sorry for the blurryness on the underneath photo (measures 72mm on the frame part where the bb goes, not sure of term here). The original bb is a square tapered, measures about 81mm from end to end with the cup on it as seen in photo. The bb below the original one is the one that came with the crank set and the box is for the bb that is currently installed (shimano deore ES51 118x73 bb). Any ideas on what size spacer, which side or other thoughts on what I should do to fix this problem?
Thanks for any advice, sorry for the long post