the 351w (windsor)produced from 69-mid 90's is the big brother of the 289,302,5.0 with a taller block,wider intake,bigger main bearings and mostly only cams & heads will interchange with 289,302 5.0 with minor mods, easiest to identify by measuring width of intake against a 302, the 351w block also has a vertical rib running from the behind the distributor to the bottom of the  intake. all 289,302,5.0, 351w use 6 bolt valve covers and horizontal fuel pump bolts,81 & later 302,5.0 use different engine balance so flywheels,dampners don't interchange, be careful in this area or vibration will destroy your engine!

the 351c (cleveland) produced from 70-74 shares the bore & stroke of the 351w and for the most part has nothing in common with the 351w except blue paint, they were availble as 2v (2 barrel smaller ports & valves) or 4v (4 barrel huge ports & valves) identified by 8 valve cover bolts and vertical fuel pump bolts and the top water hose goes to the block, the 289,302,5.0 351w water hose goes to the intake.

the 400 or incorrectly 400m  2V only, produced from 71-82 is similar to the 351c, but uses a taller block,wider intake,bigger main bearings. they share 2V heads,cams,valve covers,oil pans,front covers,distributors, which are basically 351c, the 400 has 429,460 bellhousing bolt pattern and specific engine mounts , best identified by intake valley width, 351c Valley width measures 6-31/32", 400 measures 8-17/32"

the 351m (75-82) 2v only is basically  identical to the 400 as it is a simply destroked 400 using 351c,351w bore & stroke. not easily identified,looks just like a 400, easiest to identify  by measuring the stroke, 351m is 3.5 & 400 is 4.0, cut & paste the links below to veiw casting numbers for cranks,etc.

note: the 66 up 289,302,5.0,351w,351c all have the same 6 bolt bellhousing pattern and share engine mount bolt patterns.

the 351 cleveland  is not a "big block" it has a shorter deck height than the 351windsor. the 400 & 351m are 'bigger' cleveland engines

these links should be helpful if you have a 351m or 400

 http://home.earthlink.net/~bubbaf250/parts/parts02.html

http://phystutor.tripod.com/stang/engines/cleveland.html

food for thought

did the boss 302 have 351c type 4v heads or did the 351c have boss 302 type heads?