in my truck, i am able to get to almost 65mph in low gear. i have a 14 bolt and dual wheels and was wondering what the highest ratio was that they put in it in any year. i would also like to know how low of gears i could go and be able to achieve 65 mph without haveing the rpms too high? if it helps i have a TH400 which i belive has a 2.48 first gear.

 

Does your truck still have the RPO code sticker in the glove box? If it does look for a code beginning w/ H I think. and PM me w/ that or a list of all the codes.

Most axles also have tags on them or are stamped w/ that info. I'm not sure about 14Bolts though.

As a last resort pull your diff cover off and count the teeth on the ring and pinion gears. If it has been sometime since your gear oil has been drained and replaced this could be good PM.

Hope this helps