I have a 1977 F100 with a 300 straight six (B) and a 3-speed (C), but where I get confused is the axle code states 47. I have not been able to find this in the research I have done. Can anyone help me answer this riddle? Tomorrow I'm going to clean the 33 years of crud off the axle to try and find the tag, then I'll jack the rear end up and count the turns on the drive line it takes to turn the wheel one revolution (rough guest). Thanks in advance.

 

The Ford parts manual doesn't list a code 47 for the rear axle. The codes jump from 46 to 52.
Is there any way that "4" could be a "1" ? If so, then your axle would be a 3.25 non-limited slip, 3300 lb capacity, Ford 9 inch.

 

No - it is very clearly a 47. Thank you for looking though. I am stumped. Anyone have any ideas? This is a VERY plain jane truck. It does have a radio, but that's about it!

 

Ok - to further confuse me, I found an axle tag on the diff. Here it is

3.07 D7TA-8(it counld be a B)3F

751400-1 MEX


What the hell! I know of a 3.08, but a 3.07? I can't find anything on this. I know that it was build in San Jose, but is the MEX meaning Mexico?!!!! If it is I will never live this down.

 

Here's something to confuse the issue (and me) even further. I found a 47 axle code in the Ford parts manual but it's for a 13,000 lb capacity 4.33 ratio Rockwell axle.
Definitely what you DON'T have.
Do you have a Ford 9" (removable center section) or a Dana 44 (removable rear cover)?
SOME F100's (rare) came with Dana 44 rears.
Also, do you know the DSO code for your truck?
P.S. Don't let the MEX worry you. I used to have a Dodge Ramcharger that was totally "hencho en Mexico". It carried me for several years with over 200,000 miles on the clock. Quart of oil every 700 miles and 13 mpg on mid-grade (ouch!) but it never let me down.

 

The DSO is 197774. I think it is a Dana 60 or 61 (removeable rear cover) from what I can find in research, but nothing matches with the year or model of my truck. Thanks for the help.

 

1977 is the model year. Ford started stamping the model year on the warranty plate in 1975. The DSO 74 is for the Seattle District Sales Office. I was hoping it was 90 or 99 (export).
Sounds like your rear is a Dana 44. I don't think they ever put a D60 or 61 in the F100 but not a 100% sure. I do know they put the Dana 44 rears in some F100.

 

Found it!
You do have a Dana rear axle and it is a 3.07 ratio.
D7TF-B3F= Dana 44-3 non-locking differential.
The 751400-1 I believe is the Dana P/N.
The Ford P/N for the entire rear assy. is D7TF-4001-B3F, replaced by D7TF-4001-B1F.
Still don't get the 47 axle code though. Don't get the MEX either.
Just a note, all of this information is from the Ford Parts Manual 1973/79 Truck Series 100/500 Master Parts and Accessories Catalog.

 

Thanks! I still would like to know what is up with the 47 as the axle code on the warranty plate. I've only had the truck a year (bought it for $700). I got it from the friend of the deceased origional owner. We knew him and he gave up one hell of a deal. It runs like a top and has only a couple minor dents (no rust)! It's my everyday driver.

Anyone out there know about a 47 axle code?

 

Thanks to MikeoOoOoO and NumberDummy for the info. At least I know what I have now!

Dana 44.3 3.07 ratio