I have 3:55's and no posi track, I want to get posi and if i do that i want a lager ratio....
My question is:
How much would is cost on an average to have a 3:73's or 4:10's put in or is it easy to do your self, and how about the speedo gear change, and anything else thats necssary?

Or how hard is it to find a, used rear end with 3:73 posi, or was that even stock, on any fords, and witch ones? and witch years?

Any help would be nice.

Thanks guys

 

I know the 3.73 posi was available in 99, my 99 Expy came with it!

 

Going from 3.55 to 3.73 is a waste of time; hardly noticeable. If you're not experienced at gear changes and don't have the required tools, then go to a professional. Used rear-ends aren't cheap, could be damaged(wrecks, poor care, or whiners), and don't come in factory 3.73 LS in a 8.8". A LS differential, quality gears, and installation will set you back a grand or so.

 

I just changed my 3.31's to 3.73 and added Positraction. I bought the pisotraction chunk and the 3.73 ring and pinion gear set for about $400, then I had my local mechanic install them.

I am definitely glad I made the upgrades.