Doing a engine swap in a 78 f150 truck had a 351m I'm going to drop in a 302 any run ins I'm going to run into? And what kind exhaust are you running for 302s

 

You will need to bring a transmission or at least the bell and clutch along with that 302. Different bell to trans patterns.

 

just picked up a bell and fork now I'm just wondering if stock y pipe will work I have 80 style exhaust manifold on my engine currently

 

302 is narrower and lower than the 351m. Exhaust manifolds are totally different. The y pipe isn't going to work on the 302.

 

My wife's '65 Mustang has a 302 with manifolds on it (yuck) then dual exhaust behind with an h-pipe crossover and Flowmaster Super 44s. It sounds hot, not crazy loud, but turns heads everywhere.

Are you sure you want to downgrade to a 302? My last F250 had a 302 that was performance built,headered, dual exhaust, etc, and it wasn't really enough for the truck in my opinion. It's pretty good for the Mustang, but still, it sounds meaner than it is. If you plan to use the truck for any kind of serious work or hilly terrain, you may find yourself underpowered and pissed.