1998 head identification, late or early model

[juice90]

Ok, after ALOT of swearing and 3 days of work, I finally got the head off of my 1998 Mazda B4000.

The history of the truck as I know it is, at 50,000 kms, the heads were replaced by the previous owner.. For what reason exactly I am not sure. Now at at 150,000, and when I bought it, it has a burnt exhaust valve on the number 5 cylinder.
What I am trying to figure out is, if theses heads are early model castings or later model ones. How do I tell?

Numbers on the head that I have found are C8S1A....FO91 on the front of the head, 99884 on the other side. and the other is 95TM 6090AD

 

[juice90]

Or does the reference to early model, vrs late model refer to pre 1994 heads and heads made after 1994?

 

[RonD]

Info is here: http://www.therangerstation.com/tech_library/40rebuild.shtml

There were 3 heads, 93TM were the first, the 95TM was the middle one, 98TM the last

 

[holyford86]

Info is here: http://www.therangerstation.com/tech_library/40rebuild.shtml

There were 3 heads, 93TM were the first, the 95TM was the middle one, 98TM the last

90TM heads were first, never seen a 93TM head.

 

[RonD]

90TM heads were first, never seen a 93TM head.

Yes, first 4.0l head should have been 90TM or 93TM, they are the same head.
I have 93TM on my '94