Most axles have "tags" placed between the cover bolts which will tell you the gearing, but NOT which axle it is.
Your front axle is 99.9% a Dana 30. The rear axle has (if not swapped out) either a Model 20 or a Dana 44 like Ted stated. The Model 20 is perfectly round, if it isn't then you probably have a 44...google it....you'll find photos and recognize it immediately.
The Model 20 has a bad "rap" but carries a larger ring gear than the 44. It's those people running heavy throttle that gave the Model 20 a bad rap. Yes it also has thinner axle tubing, two piece shafts, but I've known people running them many, many years. I ran one for eight years hard, I think the shafts might have been "rust welded" together...
Locking the Model 20 is where shaft seperation happens most (but not all) of the time.
Too bad you have a wide track. I have some sweet narrow track axles available with beafy axle shafts.