I'll have to check my receipts as I don't remember off hand where I purchased the main gear. As far as the cowl centering, I had no problem with the engine installation location. I followed the manual and measured carefully. I also used the kit supplied engine mounts and have had no problems so far. The only other area I got frustrated over (but was no kit problem) was installing the cabane struts and their hold down attachments in the wings. It just takes some time to get things properly alligned and squared up. I hate to build, but really did not experience any real problems with this model. You will thoroughly enjoy this model with the 150. Take offs are straight with very little rudder input and it lands like a dream. I found that the low rates were plenty for me, it snaps like crazy on low rate and is outrageous on high rate!