I believe the leaf spring perches on the corporate 14 bolt's are not in the same location as 69-72 blazers. 14 bolts came out in 73, right when GM made a width change for the spring purches.
I have a 79 1 ton pickup (single axle) with a full floater 14 bolt,,,, I can measure from to be sure. The overall width of the axle may be the same,,,but I'm almost certain the perches are going to be wider. I just went through this with a later model 12 bolt from a 78 when I installed it in my 72 blazer. So there is going to be welding to be done.
Unless you can find a Dana 60 from something even older (60's vintage?) because the spring purch width changed in 73. You might get lucky, but the search gets harder. You won't find a corporate 14 bolt with the right spring perch width because that rear didn't debut until 73.
So in other words, finding something that just drops right in is difficult at best. Plan on some welding and relocation of brackets.
71Blazer pointed out alot of issue you run into with the swap, which are reasons I considered. The biggest being wheels for me. Would have added another $800 in my case.
However, my 79 1 ton single axle has drum brakes on the rear (very large drum brakes
) So disc brakes aren't a necessity if you don't want to add that expense. That is if you can find a corporate 14 bolt from that vintage.