The biggest weakness a 300 has, is the factory cam gear.
When they were made from metal, they lasted dern near forever, but people hated the noise made by them.
They switched to several varieties of plastics trying to keep the gears quiet. Worked pretty well, but people complained when they went bad.
The latest variation seems to last around 200K on average before needing replaced. Gives a pretty good excuse for pulling the cover and replacing the front seal that has likely started leaking by then anyways, then go for another 200-400K.......

I have no clue what type of cam gear is in my engine. As I said, I bought the truck used, for a rather cheap price, and figured I would run the 300 till it was finished and swap in a diesel. A couple weeks after I bought the truck, I found a work order for the engine rebuild. It cost more than I paid for the whole truck. If they really did everything listed on that work order, this engine should have another 200K (at least) life left in it. I know I have put over 100K on it, with little more than basic PM service.

After finding that reciept, I pretty much quit looking for a diesel to swap in. I still casually keep an eye out for a deal too good to pass up, just to keep up with current pricing trends......


You may wonder why I want to swap a diesel in after the 300 is wore out. It's simple really. What else will give me the same kind of low RPM torque, but in higher quantities, without reducing the MPG? I get 12-17 MPG currently, depending on load and conditions. The same load and conditions should yield 15-20 MPG with a diesel. Maybe even more with a turbo, and my rather conservative driving habits.
That's another great thing about the 300, with the ever increasing cost of fuel, it can teach a person to drive in a fuel freindly manner. Mashing the skinny pedal doesn't really do much, aside from consuming extra fuel. Learning to use a lighter throttle foot will get you there nearly as quickly, but with a lot more fuel left in the tank....... This is especially true of the older carbed 300's.