anyone.. It IS a 77 chevy one ton dually ... 2wd and 454 /th400...
Buying a diesel.. (I have a 454 in tradce if interested.. 6.2/ 6.5) I need to buy lower gear 4.56 to high for highway travel w/ diesel..

I ma not sure what year they started making hte 14 bolt but I do know The D70 was available up till at least 82.. If you are trying to identify your axle look at the webbing on the centersection if it is a D70 their should be a 70 cast into the webbing on the lower right corner.. Another way to identify your axle is to get hte axle off the top of the right side tube and take it to your local chevy dealer.. he can tell you which axle it is and what gears it came with from that code..

Dana 70 came in the "wide-side" duallies (bed/fenders)

14 bolt came in cab/chassis trucks. These are narrower rears as teh tires are meant to stick up inder a flatbed.

I think reddwarf is right.My 77 Crew cab has the 70 under it.

RedDwarf has it dead on, I'll just add that the single rear wheel trucks also had the C14FF...