Hello.

Folks on this forum helped me ID my engine, so I feel I should TRY return the favor.

Using Doctor Dodge’s book and the section writing by SlantSixDan, I am coming up with:

1987 model year
225
Regular gas
E = cast-crank

10,000 day calendar

Friday, October 17, 1986

Please correct me if I am wrong—I don’t want to pass bad info

What makes you think it’s older?

Apologize in advance if I’m way off...

Ah yes, Dr. Watson...
That is a peanut plug head with the charge tube or AIR tube port on the firewall end of the head only found on mechanical lifter engines from 1975-1980...
it doesn't have the "offset" in the valve cover like the 1981-1987 hydraulic lifter head.... so for someone that ID's visually that would make someone
think it's not the correct engine for the truck...it would also depend on what's under the valve cover...the hydraulic lifter rocker bar and arms could be
easily installed on the 1978-1980 version of the head with the rear step down bolt, but could be drilled out and still installed on the earlier heads...

So by inference....the previous owner... replaced the original head for some reason... and could have either:
Changed the head and installed the original rocker assembly and kept on trucking...or changed the head, and changed to the solid lifter rocker assembly,
lifters and cam... (which if the owner of a 1986 truck saw the rocker arm adjuster bolts he'd also think it was an earlier engine...)

The engine stamping/date code tells the rest of the story....



It would have been funnier if it was a drool tube head on the late cast crank block....(that'd be a candidate for a nice lower weight engine assembly...)