Now, keep in mind I am a beginner at working on these trucks. I just spoke to my father in law, who was there helping me with replacing the bearings and seal, and he said the seal that came out (what was left of it) WAS a rope style seal. So, unless some 351m's came with ropes style seals, this crank isn't original!

 

Look on the crankshaft counterweights, there will be a casting number. Let me know what the number is and I'll look it up and see if the specs say anything about the seal. It should be something like "3M".

 

I have to run to the grocery store for the wife and then I'll check. Is there a specific area on the counterweight I should be looking?

 

Usually either first or second (I think it's the first) counterweight.
It's been so long since I worked on an engine that had a rope seal I went back and did some reading, most of it I remember, some not.
All the threads I looked at said that you can replace the rope seal with the neoprene style. The one thing they all mention (and one of the things I forgot) is in the groove that the seal sits in, in the main cap, there is a little spike that needs to be removed. This spike was used to keep the rope seal from spinning.
Here's a post from another forum on the subject:
If you have a rope crank, the rubber seal will weep a little. The rope crank has small slashes(couldn't think of any other way to describe it) that help drive any seepage back into the block.....There is a rope crank seal installation kit that you can buy at NAPA....I have never replaced mine but I do know that I have a rubber seal and a rope crank...It will leak a smal amount ....enough to annoy the heck out of you but not enough to get on your back and replace it....good luck!!!

Also, this is a 390, but this is what the casting number should look like:

 

I don't see a spike in the cap, so that would lean more in the direction of the crank being swapped.



The stamping is 1KA

 

Just looked it up! 1KA is a 5.8l M

 

I'm starting to, well, I'm already confused, but this is adding to my cofusion.
According to my chart, "1KA" crank is a 351M.

EDIT: I see you beat me to it.



<table bgcolor="#cccccc" border="1" width="580" cellpadding="10" cellspacing="2"><tbody><tr><td align="left" valign="top" width="21%"> Model Year
</td> <td align="left" valign="top" width="24%"> Part Number
</td> <td align="left" valign="top" width="20%"> Casting ID
</td> <td align="left" valign="top" width="35%"> Notes
</td> </tr> <tr> <td align="left" valign="top"> 1971
</td> <td align="left" valign="top"> D1AE-6303-A
</td> <td align="center" valign="top"> 5M
</td> <td align="left" valign="top"> Original 400 crankshaft.
</td> </tr> <tr> <td align="left" valign="top"> 1972-1973
</td> <td align="left" valign="top"> D2AE-6303-A
</td> <td align="center" valign="top"> 5MA
5MAB
</td> <td align="left" valign="top"> 400 crankshaft, car only.
</td> </tr> <tr> <td align="left" valign="top"> 1974-1977
</td> <td align="left" valign="top"> D4AE-6303-B
</td> <td align="center" valign="top"> 5MA
5MAB
</td> <td align="left" valign="top"> 400 crankshaft, car only.
</td> </tr> <tr> <td align="left" valign="top"> 1975-1976
</td> <td align="left" valign="top"> D5AE-6303-A
</td> <td align="center" valign="top"> 1K
</td> <td align="left" valign="top"> Original 351M crankshaft.
</td> </tr> <tr> <td align="left" valign="top"> 1977-1982
</td> <td align="left" valign="top"> D7AE-6303-A
</td> <td align="center" valign="top"> 1KA
</td> <td align="left" valign="top"> All '77-up 351M car and truck.
</td> </tr> <tr> <td align="left" valign="top"> 1977-1982
</td> <td align="left" valign="top"> D7TE-6303-A
</td> <td align="center" valign="top"> 5MA
5MAB
</td> <td align="left" valign="top"> All '78-up 400 car and '77-up 400 truck.
</td></tr></tbody></table>

 

I think I just got the wrong seal to begin with. A rope style one came out and it's a rope style crank. I just went on Autozone's cite and they offer both styles When I went in to buy the seal they said" two piece?" I said "yeah". Why no spike in the main cap? What's to stop the seal from spinning? Am I over thinking this?

 

This one has me more than confused. I'm not sure how to proceed (that really annoys me ).
The main cap is set up for a neoprene seal, the crankshaft has the hash marks in it which, to me, would seem to indicate it was for a rope seal, but as far as I know 351M-400's only came with neoprene seals.
Replacing a rope seal is a little more difficult than the neoprene. You need a tool called a "Chinese finger", at least that's what I call it. Its a small tubular shaped wire mesh with a T handle on one end. You slip it in the upper groove of the seal. You then put one end of the rope in the tube and start to pull. As you pull, the way it's designed, the finger grips the seal tight. The harder you pull, the tighter it grips. Once the seal is started in the groove, continue to pull the seal and rotate the crankshaft at the same time, this makes it much easier to feed the seal through the groove.
Once the seal is all the way through, take off the installation tool. Take a razor blade and trim both ends of the seal flush with the block.
For the seal half in the cap, install the seal and take something round and relatively large in OD (like a piece of pipe) and compress the seal into the groove then cut the ends of it flush too.
Add some RTV to the cap like on the neoprene version and install the cap
and torque. Also, put some grease on the seal. This will keep it from burning out on start up.
I'm just not too sure how critical that little pin is to operation.
I'm hoping someone more familiar with this will chime in.

 

Here's a link to KD Tool's version of the tool. It also includes the corkscrew to remove the seal. You don't need that part but I couldn't find anyone that sold just the installer.
Automotive Specialty Tools - KD 492 Sneaky Pete Oil Seal Remover/Installer

 

Subscribed...fascinating discussion and I'm learning a lot!

 

Got one of those! I didn't know it, but you'd think the parts store would know that tool is used for the rope style and not the rubber one.

 

With today's "revolving door" employees, it's not surprising.

 

I started a thread over in the 335 series forum to find out if the cap should have the spike.
https://www.ford-trucks.com/forums/1...-oil-seal.html

These parts guys are gonna love me! the first seal was in backwards (they don't know that) I called to see if they had one in stock, they said they did. I ripped apart the truck and went down to exchange the seal and they couldn't find it. A truck from another store brought the seal to my local store last night. I opened the box to find that both seal halves were damaged. They just called me to tell me my replacement for that one was ready to be picked up, and now I have to tell them I need a rope style

 

Man, this bites! Everything that I've read, also says to remove the "spike or pin" if converting to the rubber seal. So, the spike isn't there, but it doesn't look like anyone removed it. If I use the neoprene seal (even if installed correctly) it will always leak a little if I go with the rope, it might not hold up without that spike