i recently came across a mitsubishi laptop it's a 286, i can remove it and was wondering if a 386sx would fit in it and run? as well there is an external floppy disk connector on the back, is there anyway I could connect a HD to it? Thanks for any info? just for learning experience and play!

Not too likely - even if the chip fit (which I kind of doubt) the BIOS wouldn't know what to do with it. 286 chips came in a variety of forms, as did some of the early 386 cpu's - some photos here. FDD cables are not the same as HDD cables - should have some way of connecting a hard drive internally, although laptops are tricky to work on. I've got one old 286 laptop - iirc, the connector was an odd one. Desktop models are a bit easier to learn from - laptops are pretty tightly packed, usually lacked expansion slots, hard to upgrade - at least the older ones. Have fun though.