Hello everybody love this forum learned a lot many thanks !
My F100 66 had a 275 rear gear and I'm going to change it, the older guy that had it before me had changed it out. It is a 3 on the tree with OD transmission.Any Suggestions ?

 

 

Also, What engine and What tires are you going to run? My '66 has a 240, 3 speed and 235/75/R15s, and 3.50 gears. Drfinately wish I
had an OD for the highway but I wouldn't want to go much lower than what's in it now when I use it as a truck

 

9" rear axle with 3 M/T & Overdrive: 3.50-1.

 

Thanks everybody My 66 F100 has a 390 HP running 15 inch tires, what I was thinking if the OD transmission went out and I had to change to a regular 3 speed I didn't wont to be to low geared I have a 389 i was going to use that but just don't know maybe 325 ? Will be drove very little maybe on a weekend that's about it I live in the mountains of Virginia.

 

I like 370s or 389s either one works good behind 292.

 

3.50 I would think to be the best gear ratio for your rear end. I have a C6 3 speed (no OD) and run 4.11 gears.

 

Thanks everybody for the replies

 

Just to add, what they were looking for as information on tire size, was the overall diameter (or more specifically "rolling diameter" of the tire. Not just the 15 inch part, but all the other numbers.
The size of the tire is pretty much the most important part of any gear equation, with intended use and transmission type right up there, but not any more important than overall tire diameter.

Of course, engine torque and intended use are critical to making the choice, but tire size is what gets you your ultimate number for calculations.
A tire with a diameter of 32" is going to prefer completely different gearing than one measuring out at 28" for example.

Sorry, I know this was already put to bed a week ago, and all the advice was probably spot on. But I wanted to throw that out there in case it had to come up again in discussions.

Paul

 

66 f250 4x4, 300 with offy 4 bbl, edelbrock carb, EFI manifolds and soon to have a 240 head swap. 3 on the tree and 4.56 gears. I like the 4.56 gears because I like pulling, pushing, hauling or climbing anything I want. Anything.