Some observations on my Sept 1921 frame. I'll start by saying that I have a pair of 14 style 3 bolt cast iron muffler ends that had broken mountings that I ground off so could use the press steel brackets. I am planning on using it so I can mount a tail pipe.
So here are some things I have found out about my frame:
It has the pressed steel channels for the running boards but the holes are there for the forged style.
It has the pressed steel firewall brackets but the holes are there for the forged type.
It has all the holes for the front and rear cast muffler mounting bolts, including the holes in the top of the frame for the pressed steel brackets of the 09 to 13/14 muffler.
I wonder what the latest date that all the frames still had all those hole in them, not counting the 26-27 frames?

I should think you would have to see if the BFR has a change of record. That may be a tall order.

Mark,

From: http://mtfca.com/encyclo/C-D.htm#Chassis1 Bruce has the summary of:

From: http://www.mtfca.com/discus/messages/179374/250201.html discussion of early 25 frame.

From http://www.mtfca.com/discus/messages/179374/199756.html?1300932995 the 1921 cars – overlap when either forged or pressed steel running board brackets were used – probably (that would be a guess) depending on which branch plant/location as they continued to use up the older style parts. Note suppliers may have still been on contract to supply the older part also – until the filled their order. I don’t know if Ford produced all their running board brackets in the 1920’s or not.

Phil Mino posted some excellent 1921-1925 frame ID photos at: http://www.mtfca.com/discus/messages/29/12464.html as well as other info at: http://www.mtfca.com/discus/messages/29/26547.html?1175373132

I would welcome additional information and documentation. And Jack you are correct that the Benson Ford Archives most likely would have those drawings and change cards that would document it clearly. I’m sure there will be overlap but perhaps we can better document the approximate time frame. For the two piece valve cover engines and one piece valve cover engines Ford produced both months. Exact dates are in the engine production (serial number listing) in Bruce’s book and CD.

Respectfully submitted,

Hap l9l5 cut off

Hap;
Thank you for the information. After review, gives me and others a bit of information on what to look for if we need an early frame or the correct frame for even our later projects. It's nice that I will not have to add any holes to use the muffler that I am planning to use.