Are older Ford 300CI I6 engines basically the same?


We have a Go-Trac tracked vehicle from about 1974. This is close to a Nodwell 60 It has a Ford straight six 300 in it and we may need to put a replacement engine in it. Being that it's in a track rig, the engine sits down in the frame half way below the floor boards of the cab between the seats and there's not a lot of room to work.

Obviously, we'd like to get the same engine that will bolt right up to the motor mounts, bell housing, clutch and so on without trying to doing modifcations in the tight space.

Considering the track rig mfgs sometime put in whatever engines they had laying around or could get at good price, I'd guess the engine dates from 1970 to 1974. During that period, were all of the 300s the same? Does anyone know what date ranges, from that period, that all of the engines mounting points should be the same?

If it will help I can post pictures of all the casting numbers and the exhaust.

I've sent the info I have to a couple of junk yards and they haven't been able to identify it - they say the engine is older than their information. One national engine builder back on the east coast says they can supply me a complete rebuild (minus the bolt-ons) for about $3,400. I don't mind the price of the engine so much, but the cost of the freight to Alaska does get to me.

Any help is appreciated.



New member
It has a Ford straight six 300 in it and we may need to put a replacement engine in it.

The 300 6 was maybe the most bulletproof engine ever utilized by any manufacture. As such you really need to see if you can get the one you've got to spin up before wasting any more of your time contemplating a replacement.


New member
From my research, a lot of the cat vehicles with the Ford 300 six have the Industrial variant of the engine.

This one, at least in dump truck trim, had a high-flow exhaust manifold and a forged crankshaft because they expected the engine to basically live at 3600rpm.

Definitely a reliable engine. I am glad that the cat I finally got (a Nodwell 60) has that engine!

If you can get the engine in your cat rebuilt, if it can't be resurrected, it's definitely worth doing. If not, check to see if the crankshaft has the wide parting line (indicating forged instead of cast) and, if it has it, rebuild it and stow it in cosmoline for the next time. Make sure the engine you get, if you plan to keep the cat, has the forged crank.