How to identify the year of an axle

[nutt7]

On Craigslist, I found a guy selling a rolling frame for a buddy of his. He said once that it is a 76 3/4 ton, and another time he said it was a 70 3/4 ton. I don't think he knows for sure. How can I know from looking at the frame and axles if they are pre or post 73 axles? I want them for my 89 burb with no perch relocating and all that, but I want to make sure they are the post 73 types. (14bff, and mostly a direct bolt-in)

Also, can I check the gear ratio by lifting the axle and spinning the wheel once? For example, if the truck has 4.10 gears, if I spin the tire once, wouldn't the drive shaft make 4.1 rotations? or am I missing something? I would rather not pop the covers on this guys property if I don't have to.

 

[NorCal_Chris]

easiest way is to take a tape measure to them to find out width.

and i would pop the covers on the axles before purchase no matter what.

you dont know whats going on in there untill you see it. could be full of rust and water then you have a nice boat anchor.

 

[GreenieK30]

Dana 44 front axles have ID numbers stamped on the tube. Ring gears have the date stamped on them too. Post pictures and we can tell you the years.

 

[b454rat]

A 76 should have a big hub 44 maybe a small hub (can't remember the cut off), but will have a 14ff with the smaller drums. The 70 will have an Eaton rear and a 44 front with drum brakes and closed knuckle.

The 76 axles will bolt into your burb.

 

[tRustyK5]

A 76 should have a big hub 44 maybe a small hub (can't remember the cut off), but will have a 14ff with the smaller drums. The 70 will have an Eaton rear and a 44 front with drum brakes and closed knuckle.

The 76 axles will bolt into your burb.

^^^ this...and definitely open those diffs up as a condition of sale. If he wants to sell he should expect people to want to inspect the internals. Frankly he should have the diff's drained, cleaned and covers on finger tight so any number of prospective buyers can come have a good honest look.

Rene

 

[nutt7]

Thanks everyone, I will be sure to open the covers anyway. It seems the most obvious tell would be the drums in the front.

 

[4X4HIGH]

The front axle is a direct swap no matter what year the axle is (you don't want a closed knuckle axle though or one with drum brakes), the 14ff wasn't offered until 1973 so unless it came from a 1 ton truck it too will be a direct swap (assuming you also get the top spring plates) but will require a conversion u-joint.

Also, every axle has a BOM number on it (Bill Of Materials) that tells the year, what it came from, gear ratio, and if it had a locking diff.