Hello Everyone, my first post on the forum.
Farmer and Ford truck guy for life.

Have a 1980 F700 370-4v, 5 speed 2 speed axle, purchased new, blew a steering tire this summer and because of insurance thinking it was totalled for a fender and a grill surround, I bought it back to fix myself. So why not go to tilt nose? Lots easier to work on.
Found a 1989, chassis cab, F700, low pro, with the 6.6 diesel, straight 6 speed and Air conditioning, what's not to like about that! It's a donor truck only the rear frame is absolutely rusted junk, but the cab and hood are pretty nice and the 6.6 was overhauled about 25k ago. Also the diesel is a step nicer trim package, stainless mirrors, chrome bumper, stereo, cloth seat full floor mat, rear cab insulation. Just a nicer truck. Except for the Lucus-Girling brakes, which I hate and these are junk.

So in the process of taking 2 trucks and making 1.

Using the 80 chassis, the 89 Engine and trans cab and hood. Was talking to a fairly knowledgeable friend and mention we are gonna try to keep the 2 speed axle. He said that you will never get any speed out of it as the gas powered 2 speed will be geared lower. This has me curious.

The 80 axle code is E3M. Which I believe is a Eaton 2 speed with 6.50/9.04 ratio. With a 7000# front.

But the 89 I can't find the data for. It is code 5WM.

How far off am I gonna be ratio wise?


If it helps the Vins are as follows

1980 F700. D70HVGD5693

1989 F700. 1FDNK72P8LVA15464

Thanks in advance

John

 

Welcome to FTE!

5WM
5W = Not found. I find a W5. Please recheck.
M = Ford 7,000 lb capacity front axle, steel, with power steering

The Bill of Materials PDF is missing for your VIN, but I did find a '90 LN700 with the 6.6 and a 6 speed direct showing a 4.88 axle on 10.00x20 bias tires..... So that probably is about what you've got.

You can crawl under it--if you dare--and look for a placard on the housing, driver side front, and for number cast into and stamped into the pumpkin. Usually the ratio is stamped above the pinion if it's there, and also usually appears on the label.

And you are on the right track. The gasser ratios will leave the oil burner sporting one of these

 

Well 5W is what it is.

It's a low profile truck with 19 inch tires. Wonder how far from bolting up my Clark 5 speed would be?

 

Found the tag on 6.6 diesel axle. 5W. Is 3.73!

Yikes!