calling number dummy,
I've been chasing a ghost. I've read about forged internals for the 300 and references to casting #'s but no actual part numbers for steel crank and rods.
Application is rumered to be the 600 series and larger trucks with the 4.9 engine. appreciate any insight on this. Thanks svj

 

Here's the 1965/72 240/300 crank (6303) info. Since truck series not noted, info applies to all including Econoline.

1969: 1st year Econoline available with 300.

 

Thanks for getting back to me, As I look at the bearing chart I see a reference to 300 L/D & H/D. Light duty/Heavy duty? The scuttle butt I read suggested the F550 - F750 dump truck & straight trucks from the mid 70's to the early 80's could have a 300 cid engine that had a higher RPM working range and that these engine had steel cranks and connecting rods, possibly forged pistons. These are parts i'm trying get my hands on. Please let me know if there are #'s for these parts or if this this is an urban tail.
I've put a 300 from a '76 in place of the '66 240. It's been hopped up a bunch and these parts would be a nice improvement. Thanks, svj

 

OK I get it that part no. was so short I thought it was a casting no. so what makes the difference in the h/d motor and the l/d motor.

 

OK; It's time this old timer to start wearing my specs I see the crank no.s down at the bottom of the page, (and yes, I do feel stupid.) So great one, do you know of a source for each of these the C5TZ 6303-D (according to an old issue of car craft a heat treated iron crank?) or the C6TE 6303-G (according to this parts list a steel crank)?