Anybody know what would be a good donor car to convert my 70 cougar 351w to serpentine system?
I used a system off a Fox T-Bird. Fox Mustang works too. However, since it’s only a 5.0, the power steering and AC bracket needed to get modified to reach the mounting positions in the driver’s side cylinder head due to the taller deck height on the 351. You’ll also need a reverse rotation water pump and custom upper and lower radiator hoses. Compound that with the reverse water pump having the inlet on the opposite side from stock which also requires some custom radiator work.
Other than that, it’s a bolt on. 
Ok cool… What year should i be looking for an also what harmonic balancer should be used? I’m not really a Ford guy, worked selling parts for Chevrolet dealer for 16yrs. This 70 cougar is a project i found to replace my 69 cougar i sold back in 1993…
The other issue I failed to mention is that the later model serpentine systems, and by later model I mean 80s era, use a four bolt crank pulley. Your balancer accepts a 3 bolt. My apologies in advance that I do not know off the top of my head which balancer will work for your application. My engine had a 4 bolt balancer already on it.
As for years, mid 80s were the most popular for the Fox era. I’m running an 88 T-Bird, but anything Fox V8 from say… 84-88 would be a safe bet. Possibly even earlier than 84. But I know 84 and up for sure.
I suppose you could also check out F150 trucks that already have a 351 in them as well. My Dad’s 95 had a 351 with a serp system too.
Buy the kit from March or some of the pulleys you might need. Not the most cost effective, but would be pushing the easy button. Be mindful of the water pump rotation, standard vs reverse.
https://marchperformance.com/ford/ford-small-block-289-302-531-windsor/pulley-and-bracket-kits.html
'70 351W uses a 4 bolt crank pulley and drivers side water pump outlet, which simplifies this swap. ('69 uses 3 bolts and passenger side outlet.) All years of 351W balancers are weighted the same (28 oz imbalance.) So if you do end up changing balancers (and if you’re still running the original from 1970, its overdue), you don’t have the 20/50oz issue to contend with like on a 302.
Sometimes 351W accessories use the same brackets as a 302, with an adapter between the bracket and engine to make up for the difference in deck height. Sometimes they use different brackets. But so long as everything comes from a 351W it should fit.
Passenger car 351Ws from the serpentine belt era are relatively scarce, but they’re common in light-duty trucks from the mid '80s through mid '90s.
GREAT info!! 
This is my 1969 351w and I converted it to 70 four bolt and bought the March kit. 302 reverse rotate pump so it’s on the driver side. I think their is a short/long pump option. Can’t remember what I bought for a balancer and would have to look it up. I had to change to a newer timing pointer. Since the photo I went to a bigger Alt pulley to slow it down as I hit 6,800 rpm on the track.
Cool thanks for all the info!!!
I used the kit from CVF Racing. Make sure to measure the distance between your engine and radiator to make sure there’s space for your fan. I had to go with a slim electric to make it all fit.