Re: How to track down source of engine
I've been searching around and cannot find an engine decoder, or parts number decoder that seems to fit the pattern of that number. although i did do some quick searching on the f-100. it seems that the only generation of the F series pickup truck with a 351W and a f-100 model was between 1980 and 1983.
at the end of 1983 the f-100 was dropped as the base model and the f-150 became the new base model for the f-series trucks.
and 1980 - 86 ( seventh gen) was the first generation of f-series trucks that had the 351W option in them. as the 351W replaced the older 351M option.
however, this was just a quick find on wikipedia and this of course is public edited so I cannot completely verify the information to be 100% correct. its the best i could do though, hope it helps.