351c is a small block.
It takes a small block bell c6, or a c4, or an AOD (like I have bolted to my 351c) or a t-5 or a small block toploader etc.
Please don't confuse the 400m when ford destroked it to make the 351m with a 351c

On edit i added a source: http://en.wikipedia.org/wiki/Ford_335_engine
Even though it isn't really needed.

 

Who cares whether you call it a small block or a big block. Those are really GM designations anyways. I have a 351 Cleveland and I love it. If you aren't planning on rebuilding/building for power I would guess the Windsor would be better though. A stock used Cleveland has too much of a chance of the bearings being bad. If you could somehow here it run and be sure that it doesn't knock then the Cleveland might be better. Granted there's nothing saying that the Windsor doesn't have bad bearings too, just less likely. I wouldn't worry about the lack of performance parts available on the cleveland. The only thing original left on my Cleveland is the heads and that's just cause they are good stock heads. The Cleveland can probably make more power cheaper...

 

but that was an FE engine, the ford 335 series of engines 351c, 351m,400m was built by ford as a second alternative line of small block engines for use in performance and truck applications. they do share some similarites and part interchange with the windsor and 385 series but they are small block motors and are listed as such by ford motor company. They put the c6 on the cleveland because it was for the most part the standard truck trans at the time and so ford used it on the cleveland in cars as well.

 

it was a small block from 1970-1982, what about before then?

 

it wasnt even in existance until 70 70-74 for the cleveland and the others lasted till early 80's

 

the cleveland isnt a big block it is a "big" block although, it is the biggest small block ford had too offer. there are alot of differences, i would choose the clveland overall not only cause they are rare, but because they are torque monsters. the heads were good enough from factory, not too restricting and theyhave "canted" valves to alow more airflow. check the several thousand threads in the 351 section about the W vs C debate. i dont feel like typing everything right now

 

i would go with the cleveland. do you know what year the cleveland is? 2 or 4 v heads?

 

the cleveland is an early 70's. but nobody has answord my biggest question.....will it even fit in my '68.

 

Cleveland STYLE heads have an advantage in cantaed valve designs, but actual Cleveland heads suck by todays performance standards. I don't know HOW MANY FREAKING TIMES I HAVE TO SAY THIS, but even the smallest aftermarket Windsor heads like AFR 165's and Edelbrock Performers OUTFLOW even 4V/BOSS Cleve heads up to .600 lift, and that's with a WAY smaller port, which means higher velocity and more power. 30+ years ago Cleveland heads were better than pretty much anything out there, but guess what.....THE HEADS ARE STILL 30+ YEARS OLD!! If you already have a Cleveland then fine, build it, it's cheaper than buying a whole new engine. But unless you have the money to buy good heads for a Cleveland, Edelbrock Performer RPM Cleve heads AT LEAST, you're NEVER EVER EVER EVER EVER EVER going to get the same power out of a 351C as you will from a 351W for the same amount of money and rpm range. A Cleve will cost more to getthe samepower in the same rpm range. Simply put, the stock heads on a Cleveland are a crippling performance factor by todays standards. If you put good heads on it(none of which are cheap) then it will make good power.

 

67 302, CHI cast iron cleve heads for a cheap alternative or Blue Thunder Cleve heads and a good manifold...and comparable windsor and cleve heads are around the same price point, you can easily get low rpm power out of a cleve its just most people unfamiliarity andinexperiencewith a big port higher rocker ratio big valved motor tends to lead to the misconception of low rpm power robbers.If a cleveland is done right which most of the time they are not it can be a very very good thing i mean were talking unreal power band.

Remember its not how much you pay for the parts, its paying for the right parts.

And yes it will fit your 68 may have a little fittament modification no matter windsor or cleve