I am currently swapping out a 302 and installing a 351 into my '92 F150 4x4. I know manifolds are different and y-pipe connections and geometry are different. 351 has a larger collector diameter and I assume larger head pipes. I am looking for sound advice. I can't get the 351 y-pipe from a salvage yard because it is all attached to the converter and they can't sell salvaged converters here. I am thinking about taking it to a muffler shop and hacking the head pipes off at the cross-over point and welding in new larger pipe to match up to my manifolds. Bassani makes a stainless cat forward system but it costs $360 plus. Checker has vendor that has the cat forward for $250. The 302 exhaust has the O2 sensor in the crossover connector pipe. I was planning on keeping that in place. I don't know where the 351 exhaust has the O2 sensor. I want to use the 302 wiring harness which has a single O2 sensor at the crossover. I have speed density and am planning to use the 302 chip in it if it will run with it. I've read some swappers say it will and some say it won't, I will cross that bridge when I get there. I have to pass emissions here.

 

the walker 40370 crossover pipe should fit your manifolds.
it is for a 77-78 f150 with 351 windsor.

it is a regular crossover with no converters attached.
the sensor could be fitted to the pipe without too much trouble.

something to look into anyway

michael

 

Thanks for the info, but I already purchased a Catco OEM replacement for 351. It turns out there is a large aftremarket for cats. I googled Catalytic Converter and was led to several sites. I bought an OEM rel;acement that uses 1 cat instead of the stock 2, single O2 sensor in crossover, plus it is made of mild stainless steel! Free shipping and it only cost $190. Collector bolts right up ( on the engine stand, engine not in truck yet).

 

good luck and i hope it works for you