I have 1985 ford f150 2wd with a aod tranny with a 302 what size motor can I up grade to without changing the tranny for more power

I believe a 351 will drop right in.

thankyou,is there any years that are interchangeable for the 351

They make AOD shift (reprogramming) kits so you can go with more power. An example http://www.transmissionpartsusa.com/AOD_Transmission_shift_kits_s/12284.htm

351 CID Windsor V8 1983–86, 351 CID HO Windsor V8 1984-86. You will have to change over the electronics and a few other minor things to make it work.

Yes it will the 351W is a small-block, up to 1997 when it was discontinued in favor of the 4.6 but Ford began using fuel injection in 1987

Not to be confused with the 351 Cleveland, a completely different engine

Wow I learned something today! I had no idea they made the 351 that long. Thanks Fordnut. Since I learned something already today I can turn my brain off and look forward to the weekend, LOL

It was not in trucks after 1986, Mustangs and some others though

Ahhhh ok. So I'm not totally losing my mind, LOL.

It had a different cam and heads, and valves, from '86 to '97 for the cars sacrificing some low-end torque for more HP for the cars

Well that does make sense. I thought the Mustangs had 302's in them until 1993 when they ended the Fox body? The 351 in the crown vic, Marquis, Town Car and Super Duty trucks makes sense.