I found a good deal on a clean low mileage 94
300 six and apparently ordered with a c6

Making camper for my dog and I with it.
I have a 18 foot boat trailer that I made into my bike hauler and tool chest.
With a 3.55 diff and 235/75r15 tires she has plenty of grunt to get things rolling.
At 65 or 70 the motor is singing pretty high lol.

I want to drop the diff down a bit.
Mine has the speed sensor in the pumpkin.
does anyone know what years will have the same speed sensor?
And I have been trying to find a chart on ratios offered in the axle for this year.
So far looking through junkyard all I have found were...
3.55 373 and 411

I think the 3.55 would be fine with od trans.
What were common ratios?
3.08?
And what years would be compatible to the speed sensor

 

You didn't mention what is the engine speed at 65 mph.You are correct, the C6 transmission has no OD. Myself, I would leave the 3.55 gears and transmission alone. I think the next gear set would be 3.27 but I am not sure on that.. I know you will be very unhappy with 3.08 diff gears and the 4.9 is no speed demon..Reason being as a camper, it will be heavily loaded and likely will be driven in hilly areas. I think you are in good shape.

 

I do not have Speedo. I think a 3.08 might be to stout too.
I want to drop it down to around what it would be in overdrive.
So not a radical change.
Just like to know what was available.
Lord I'm to old to go on a wild goose chase
Lord I've owned a few of these over the years.
Most have been f250 with t18 and 411.

I know she can drop a bit and be ok.
not really that heavy. Loaded light lol.

Anyways does anyone have a list of options for ratios?
And what years the sensor was the same.

 

You can go to Rock Auto's site and lookup speed sensors for various years and see if the part numbers match. I don't have the time to do it for you.

 

Good idea!!!!
I hadn't thought of that.
I have been searching threads on forums like this.
Doing the math...ratio charts acually.
70 mph has me turning about 2900.
By ear I think it sounds about the same.
Doing chart with a sod ratio of .667 of
70 is churning about 1450 in od.
I'd like to split the difference.
Drop it to about 23 at 70.
Still a bit high ....but it should give me grunt at lower speeds too.
I look up rock auto thanks for the idea.

 

You probably are revving a little higher. My f150 4.9 w/OD and 3.55 rear end shows about 3k on the tach going 65mph.

 

Oh ok. Any idea what your od ratio is?
auto or stick?
I looked up speed sensors
There isn't any specific one for ratio.
The count must be on the spline.
But......it did give me years that use the same sensor.
91-97. It gives me a better range to hunt for.
Looked up diff gears to 3.54 4.11.
And a 4.73.
I will redo search using a 94 with a 351 engine.
I am sure all will be geared to the of trans.
But maybe a v8 might have a lower ratio.
Just a thought but when it was ordered with c6 tranny.
They didn't compensate for a 1to1 trans.
I will do more looking.

 

This site may help you ID differentials and what is available if you go boneyard searching.

https://www.fordification.com/tech/rearends_ford15.htm

 

Well after a road trip from Texas to Indiana I think I could use a bit more gear.
loaded and pulling the trailer I averaged 14mpg.
I cut north in Arkansas through some good grades.
I just hold throttle steady and she pulls good.
Speed drops but pulls steady.
A few grades I dropped to 45..but just pulled in slow lane with the big trucks.
If I mash the throttle she will maintain speed.
And will accelerate up the grades.
I just held her steady to conserve fuel.
I will check junkyard here and see what's available.

Not sure how it will affect shift points.
This is controlled electronically even though it's a c6.
they have a vacuum pod that is controlled by computer.
Instead of being hooked to intake.

Just have to try and see lol

 

I don't believe there was any C6 which was controlled electronically.It's hydraulically controlled, no solenoids inside. I have put many hundreds of thousand miles driving 1988-1994 Econolines with the 4.9 for business purposes.I was lucky to get 15mpg.
If you got 14 mpg with your van loaded up like that,in hilly terain and pulling a trailor, that is very good. I don't know what you are expecting. Good luck improving on that.You likely will end up with something that can barely make it up a hill loaded up.