If it's a '94 rear DRW (pickup) axle,I can assure you,it's 4.10.
Those are the only ratio offered in the DRW pickup's in the 9th gen era.You could get 3.55 in the F350 cab and chassis of the 8th and 9th gen era.
3.55 of the 8th gen era in the SRW,DRW and cab and chassis but for whatever reason ford didn't offer anything but the 4.10 ratio in DRW pickups in the 9th gen trucks.If you see a '92-'97 dually with a pickup bed on it,it sports 4.10's.
Many salvage yards may claim to have them but when pressed to inspect them,you'll never find one.I know lol.I had to get a 3.55 DRW pickup axle from a 8th gen truck for chip truck when I converted it.There's only a few years there where they come with the VSS/ABS sensor/tone ring too.
Of course,that's just some added info.Al is still correct in that it's not impossible that someone still couldn't of swapped a R&P in the rear too.You really never know until you pull the cover to look and or spin a wheel and count rotations of drive shaft and wheels........however,the odds are gunna be some high,she's got 4.10's out back.
Edit; OR,yes.Lock the hubs in and take her out on a patch of dirt.You'll know if there are 4.10's up front/3.55 out back easy enough that way too lol.
Better yet out on snow.The rear will want to come around and be the front on ya.