Some info I've kept over the years;
Windsor engine characteristics
Thermostat housing bolted to the front of the intake manifold
All 289/302/351's have intake bolts 90 degrees to the ground
289/302/351's have evenly spaced exhausts aimed 90 degrees from length of head
5/8" (18mm) spark plugs
The 351W and 302 are very different:
The 351W has a taller deck height than the 302. (a 302 will have the intake almost flush with the base of the distributor... where it goes into the block..... a 351w will have about 1/2 inch lip there where the intake meets the block.)
Since the deck height is taller the intake manifold is wider on the 351w than on the 302.
The 351W uses a larger main journal than the 302. there are 2 physical ways of telling a 302 vs. a 351w. Also, in between the frost plugs on a 351W there will be what appears to be a triangle or diamond (the way I was told) indented cast into the block...a 302 doesn't have those.
a 351W is wider between the heads compared to a 302 (the intake manifold is wider by about 1-1/2"
) and 351 pistons have a different pin height. You can use 302 pistons in a 351 if you stroke it to a 393
quick ID tip: The lower thermostat housing bolt on the 302 will be below the top of the water pump and you won't be able to put a socket on it. On the 351W you can remove the bolt with a socket.
The early 351W has four extra intake manifold bolts (13, 14, 15 and 16). If you see them, it's definitely a 351W.
The positive ID is to measure the lower intake; 302 is aprox ~ 8 inches wide. 351 is aporx ~ 11 inches wide
. The 5.0L uses squared ports and the 5.8L uses oval ports. If you get an intake from a junk yard it will have the matching fuel rail..."
Source: by Ryan M (Fireguy50)