Header question

[RandyinRenton]

Anybody know what the difference is between a 73-77 header and a 78-79 header? They reference different part numbers, and I found a 73-77 header locally. Will it work on a 79?

[]2eDeYe]

It's the port shape, and it really depends on the head not the year (we all know PO's are cheap bastards :))

 

The early style has rectangular ports and the later style has round ports.

[RandyinRenton]

my 79 appears to be bone stock, without ever having any work done to the motor so it would have the round ports, no?

[datzenmike]

Look on the head below the #1 plug where it meets the block. A '78 620 through '80 720 truck should say W-58.

[Rubberman]

don't mean to jump in, but I was taking the motor out of my parts 78 620 tonight and checked the head and it's a w58 and my 77 620 that I'm redoing has the u67. Which has the round and which has the sqaure port holes between the w58 and the u67? I've asked this question before on here, but it never will stick in my nogin.

[datzenmike]

A-87 and U-67 have square exhaust and the W-58 have round with steel liner inserts.

 

 

Here's a W-58. You can make out the light tan colored liners in the exhaust ports.

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