converting 66 mustang

have a 66 mustang with straight six. want to put a 302 in it. found a 86 ford truck with 302 and auto. i know the 302 will fit but will the auto tranny fit or can i use my existing 3 speed manual in it? and if i have to use my manual what will i need to do to make it work?

You're right that the motor will fit. I haven't heard of people dropping in an auto with a 302. They usually opt for the t5 conversion. That's what I'm putting in my 65-a 302 EFI with a t5.

Your existing 3 speed should work, but can't remember how the bellhousing works. That is whether you need to keep the original bell or get a late model manual. There's some other forums out there that will have some info on this. Just look it up on Google.