'67 Diff Carrier cast 3899143 NF

[Wayne M.]

[Joe L.]

Re: '67 Diff Carrier cast 3899143 NF

Wayne-----

I've always been inclined to believe that it's a foundry mark which refers to "nodular foundry", but I don't know that for sure. In the cast iron foundry business, usually a particular foundry will produce castings of only a certain, specific type of cast iron. For example, the old Tonawanda foundry which was co-located with the engine plant was a gray iron foundry. In Saginaw, MI there were once 3 GM foundries---the gray iron foundry, a malleable/ductile iron foundry, and a nodular iron foundry. The gray iron and nodular foundries remain, but the ductile/malleable iron foundry was closed years ago.

As far as I've been able to learn, GM once operated 3 nodular iron foundries. One was the Saginaw, MI nodular foundry I mentioned above. A second was the nodular iron foundry located in the same complex as a gray iron foundry in Defiance, OH. The third was located near Danville, IL. The latter of these has been closed for several years now. However, when it operated its casting identification mark was a "D".

So, I think that "NF" refers to one of the other 2 nodular iron foundries, both of which are still operating. However, I don't know which one it refers to.

[Wayne M.]

Re: '67 Diff Carrier cast 3899143 NF

Joe --- You're probably right about the different foundry being responsible for the "NF" as apposed to just the "N". Yesterday afternoon I found an empty carrier in my basement, cast just 15 days before the one I had originally queried and assembled AU 5-17-67, only 5 days prior to the other). After wire-brushing considerable rust, guess what ?, another NF.

So I would expect many carriers in that timeframe to bear the "NF". At first, I thought the chemistry was different, given that these were all big block diffs, and the one that initially caught my interest was a very high numerical ratio unit. Now if small block diffs in the same period also show the same cast suffix, then that seals it.

Thanks for your info

[Joe L.]

Re: '67 Diff Carrier cast 3899143 NF

Wayne-----

I can assure you that some or all small block differential housings also have the "NF" casting mark; mine does. Also, most differential covers that I've seen have it, too. In fact, the "NF" casting mark will be found on many parts cast from nodular iron including rear bearing supports, cast crankshafts, and flywheels.