help id'ing heads/engine

[oldiron]

The web has been some help as to figuring out the engine but the heads are eluding me. Everything points to a 1968 block "8D8" under the starter, c8 casting number, 8u****** partial vin stamped behind the intake. Pretty safe to say '68 for that part. Now the heads are a different story. They have the smaller 14 mm plugs, I just pulled a valve cover to find no displacement casting, and only an upside down "78" cast next to a 7K4.
Can someone help narrow this down a little bit?
Engine runs perfect/quiet/smooth. I just need to know what I have in order to get the right parts in the future.
Greg

 

[bax]

I am going to say early 302. A 289 would have a 65 cast date on the block. The casting 302 or 289 will be on the head under the valve cover.

 

[oldiron]

No displacement casting.

 

[bax]

Ok new guess. early 302 with later model heads. How many bolts go in the valve cover? Nothing here suggests it has to be a 335 series engine family other than its in a bronco.

 

[oldiron]

Further digging says either 11/4/67 or 11/4/77. With no disp casting and the 14 mm plugs it starts to lean heavily towards '77. So I most likely have a '68 passenger car block (due to the partial vin) with some highly sought after (NOT) cylinder heads. Can't complain though, it runs perfect,never overheats, and holds 45 psi of oil pressure at hot idle. Should be perfect for what I have planned.
Thanks
Greg

 

[bax]

Not a 67. You would have the displacement casting on the head under the valve cover. Sounds more like a 77. If your happy its all good.

 

[Broncobowsher]

D8, wouldn't that be '78?

Small plugs point to newer heads, at least mid 70's. I really don't know of any signifient difference between a '68 block and a '78 block. Same balance, same 2-piece rear main. There was a late 70's block with an extra hole in it, it was a crank position sensor that needs the hole plugged or you get an oil leak.

Are the rocker arm bolt down sled style, or stud mounted with the ball pivot?

 

[oldiron]

D8, wouldn't that be '78?

Small plugs point to newer heads, at least mid 70's. I really don't know of any signifient difference between a '68 block and a '78 block. Same balance, same 2-piece rear main. There was a late 70's block with an extra hole in it, it was a crank position sensor that needs the hole plugged or you get an oil leak.

Are the rocker arm bolt down sled style, or stud mounted with the ball pivot?

No 8d8 with a c8oe-6015-a
8D8 translates to april 8 1968
Rockers are the stud mounted rail type.