-1974
-f100
-2wd
-360
-Borg Warner t18
I just rebuilt the engine and resealed the transmission. When I took the drive line off, I noticed a lot of play in the rear differential. I am going to either replace the spider gears myself or buy one completed, but I wanted opinion what gear ratio would be good for cruising speeds of 70-75 mph and still be able to tow heavy loads. I currently can drive 70-80 without the engine screaming, but I'm unsure of the current gear ratio in it.

 

You should have an axle code on your door tag that will tell you what you have now, assuming it's unaltered.

Some of it depends on the tire size you're running. I would guess if you're running a stock size tire you're going to want a minimum of a 3.54 and maybe more like a 3.23.

 

08j was on the door

 

I think that's a 3.50, maybe some knows for sure.

If that's the case and you want higher gears a 3.23 or I think Ford is a 3.25 would be your logical gear of choice.

 

I currently have a 3.00 geared 9" out of a '72 F100 in my '66. The truck it came out of had an FE motor and a T19 transmission

 

With something near stock tire size around 3.50 is a good choice IMO. Reasonable cruising at highway speeds and can still tow reasonably well. If you had lots of towing I would say 4.10 but in your case around 3.50 is probably best. I would not want less gear.

 

Thanks, I appreciate all the feedback from everyone.