gear ratio?

[35thls1ss19]

i am ordering a dp tuner and its asking gear ratio? i have a 99.5 f350 auto. How would i find out what i have in the rear? Was there options or did they all coem with the same? thanks alot
-cj

[jbeasts10]

gear ratio will be on the tag on the rear-end housing..mine came with 3.73

[dieselcrawler]

there is a tag on the door that list an axle code, a number/letter combo, that will be decoded to tell you gear ratio and w/ or w/o LS rear... I think mine is "RC:21" which is 4.10 gears, L/S. It says it "axle" below it... Post that, and someone should have the list of what the codes are... I was able to find them doing a search, not sure if it's on this BB or if I found it on the WWW.