Same here. 10/74 FJ40 with engine number F562953. Same later F.5 oiling system, same holes in the head for the later air cleaner, but I have the big ol' F air cleaner. Same 2F alternator mounting holes in the head. Stamped steel valve cover, but they leaked a lot for some people (mine doesn't) and that was a common swap-out for the later aluminum cover.
I love the inline six cylinder engine and would have a hard decision to make when this one finally goes. Still running strong, but driving down and back from Portland to the Rubicon last summer was a little tough on it. Planning on the same trip this year with some additional precautions, but 50 years is 50 years. I don't really have any desire to move on from the Toyota F/2F, but they're all getting a little long in the tooth, inefficient, low HP, and quality internal parts are getting tougher to source, at least at a reasonable price.
Lots of options for relatively easy swaps that would end up about the same price or a bit cheaper than rebuilding the F motor. Swapping in a running 2F used to be a great option, but they're all old now too. If I were going to drop a 2F in now, I'd really like to go with the Mosely cop motor treatment ($$$$). Chevy small-block V8 used to be the go-to, but seems like most guys are leaning toward the more modern LS instead of an old 350 carbureted engine. The 2.8 Cummins diesel swaps were real popular for a while. Seems a little less popular now, but not sure why. You could spend hours and hours reading here about other possible swaps. No perfect solutions, just trade-offs. If the engine is truly cooked after a thorough inspection, weigh your priorities for the truck moving forward. Period-correct restoration? Trail truck with power to move big tires? Highway power for a pavement truck? Jack of all trades? Do you care about staying with a Toyota 6? Lots and lots of options, none of them cheap.
